From chemistry-request@ccl.net Wed May 28 07:04:59 2003 Received: from smtp2.ruc.dk (smtp2.ruc.dk [130.225.220.70]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SB4wKY008202 for ; Wed, 28 May 2003 07:04:59 -0400 Received: by smtp2.ruc.dk (Postfix, from userid 504) id 234A9C81C67; Wed, 28 May 2003 13:04:58 +0200 (CEST) Received: from virgil.ruc.dk (virgil.ruc.dk [130.225.220.110]) by smtp2.ruc.dk (Postfix) with ESMTP id 2F108C81C64 for ; Wed, 28 May 2003 13:04:57 +0200 (CEST) Received: from VIRGIL/SpoolDir by virgil.ruc.dk (Mercury 1.47); 28 May 03 13:04:57 +0100 Received: from SpoolDir by VIRGIL (Mercury 1.47); 28 May 03 13:04:52 +0100 From: "Jens Spanget-Larsen" Organization: Roskilde Universitetscenter To: CHEMISTRY/at/ccl.net Date: Wed, 28 May 2003 13:04:50 +0100 Subject: CCL: Orbitals Reply-To: spanget/at/ruc.dk Message-ID: <3ED4A5E2.32193.DDDB59@localhost> X-Confirm-Reading-To: spanget/at/ruc.dk X-pmrqc: 1 Priority: normal X-mailer: Pegasus Mail for Windows (v4.01) X-Spam-Status: No, hits=-3.2 required=5.0 tests=QUOTED_EMAIL_TEXT version=2.53 X-Spam-Level: X-Spam-Checker-Version: SpamAssassin 2.53 (1.174.2.15-2003-03-30-exp) Mikael Johansson: > On Tue, 27 May 2003, Jens Spanget-Larsen wrote: > > > And in principle, MOs are not physical quantities; they are model > > constructions, and as such they have no physical reality and they > > cannot be observed experimentally. > > Well, there is a lot of discussion in the literature on this topic. > A few good examples, biased towards my thinking, could be: > > [1] Stowasser and Hoffmann, "What Do the Kohn-Sham Orbitals and > Eigenvalues Mean?", J.Am.Chem.Soc. 121 (1999) 3414-3420. > [2] Baerends, Theor.Chem.Acc. 103 (2000) 265-269. > > Have a nice day, > Mikael J. > http://www.helsinki.fi/~mpjohans/ Dear Mikael! Yes, it is true, there has been some discussion on the status of the MO concept. But to me, there can be no doubt: In principle, orbitals are one-electron wavefunctions, and for a many-electron system, they do by definition NOT correspond to physical reality. However, they are extremely useful models, as we all know. The usefulness of the MO concept in rationalizing a lot of chemistry and spectroscopy sometimes leads people to think of MOs as physical quantities, rather than simplified models. Do you think my point of view is erroneous? Yours, Jens >--< ------- End of forwarded message ------- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= JENS SPANGET-LARSEN Office: +45 4674 2710 Department of Chemistry Fax: +45 4674 3011 Roskilde University (RUC) Mobile: +45 2320 6246 P.O.Box 260 E-Mail: spanget/at/ruc.dk DK-4000 Roskilde, Denmark http://virgil.ruc.dk/~spanget =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= From chemistry-request@ccl.net Wed May 28 03:50:08 2003 Received: from smtp2.ruc.dk (smtp2.ruc.dk [130.225.220.70]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4S7o8KY001057 for ; Wed, 28 May 2003 03:50:08 -0400 Received: by smtp2.ruc.dk (Postfix, from userid 504) id 77641C7EE7B; Wed, 28 May 2003 09:50:07 +0200 (CEST) Received: from virgil.ruc.dk (virgil.ruc.dk [130.225.220.110]) by smtp2.ruc.dk (Postfix) with ESMTP id 62388C7EE78 for ; Wed, 28 May 2003 09:50:06 +0200 (CEST) Received: from VIRGIL/SpoolDir by virgil.ruc.dk (Mercury 1.47); 28 May 03 09:50:06 +0100 Received: from SpoolDir by VIRGIL (Mercury 1.47); 28 May 03 09:50:00 +0100 From: "Jens Spanget-Larsen" Organization: Roskilde Universitetscenter To: CHEMISTRY|at|ccl.net Date: Wed, 28 May 2003 09:49:49 +0100 Subject: Orbitals Reply-To: spanget|at|ruc.dk Message-ID: <3ED4782D.12504.2B5051@localhost> X-Confirm-Reading-To: spanget|at|ruc.dk X-pmrqc: 1 Priority: normal X-mailer: Pegasus Mail for Windows (v4.01) X-Spam-Status: No, hits=-3.2 required=5.0 tests=QUOTED_EMAIL_TEXT version=2.53 X-Spam-Level: X-Spam-Checker-Version: SpamAssassin 2.53 (1.174.2.15-2003-03-30-exp) Mikael Johansson: > On Tue, 27 May 2003, Jens Spanget-Larsen wrote: > > > And in principle, MOs are not physical quantities; they are model > > constructions, and as such they have no physical reality and they > > cannot be observed experimentally. > > Well, there is a lot of discussion in the literature on this topic. > A few good examples, biased towards my thinking, could be: > > [1] Stowasser and Hoffmann, "What Do the Kohn-Sham Orbitals and > Eigenvalues Mean?", J.Am.Chem.Soc. 121 (1999) 3414-3420. > [2] Baerends, Theor.Chem.Acc. 103 (2000) 265-269. > > Have a nice day, > Mikael J. > http://www.helsinki.fi/~mpjohans/ Dear Mikael, Yes, it is true, there has been some discussion on the status of the MO concept. But to me, there can be no doubt: In principle, orbitals are one-electron wavefunctions, and for a many-electron system, they do by definition NOT correspond to physical reality. However, they are extremely useful models, as we all know. The usefulness of the MO concept in rationalizing a lot of chemistry and spectroscopy sometimes leads people to think of MOs as physical quantities, rather than simplified models. Do you think my point of view is erroneous? Yours, Jens >--< =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= JENS SPANGET-LARSEN Office: +45 4674 2710 Department of Chemistry Fax: +45 4674 3011 Roskilde University (RUC) Mobile: +45 2320 6246 P.O.Box 260 E-Mail: spanget|at|ruc.dk DK-4000 Roskilde, Denmark http://virgil.ruc.dk/~spanget =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= From chemistry-request@ccl.net Wed May 28 05:04:16 2003 Received: from frontend-1.cgpmail.ua.pt (mail.ua.pt [193.136.80.79]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4S94FKY003529 for ; Wed, 28 May 2003 05:04:16 -0400 X-UA: Message Inspected for Viruses by RAV Received: from [192.168.69.132] (HELO backend-2.cgpmail.ua.pt) by frontend-1.cgpmail.ua.pt (CommuniGate Pro SMTP 4.0.6) with ESMTP id 9788992 for chemistry|at|ccl.net; Wed, 28 May 2003 10:04:14 +0100 Received: from [193.136.83.38] (account ) by backend-2.cgpmail.ua.pt (CommuniGate Pro WebUser 4.0.6) with HTTP id 5381331 for ; Wed, 28 May 2003 10:03:46 +0100 From: "Nelson Fonseca" Subject: mmodgrid To: X-Mailer: CommuniGate Pro Web Mailer v.4.0.6 Date: Wed, 28 May 2003 10:03:46 +0100 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format="flowed" Content-Transfer-Encoding: 8bit Experience is what you get when you don't get what you want. -- Dan Stanford-- hello! Can anyone point me to where mmodgrid can be downloaded? Thanks! Nelson Fonseca PhD Student University of Aveiro Portugal From chemistry-request@ccl.net Wed May 28 07:53:12 2003 Received: from soul.helsinki.fi (soul.helsinki.fi [128.214.3.1]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SBrBKY009324 for ; Wed, 28 May 2003 07:53:12 -0400 Received: from localhost (mpjohans@localhost) by soul.helsinki.fi (8.9.3p2/8.9.3) with ESMTP id OAA337498 for ; Wed, 28 May 2003 14:53:11 +0300 (EEST) X-Authentication-Warning: soul.helsinki.fi: mpjohans owned process doing -bs Date: Wed, 28 May 2003 14:53:10 +0300 (EEST) From: Mikael Johansson X-X-Sender: mpjohans|at|soul.helsinki.fi cc: CHEMISTRY|at|ccl.net Subject: Re: CCL:Orbitals In-Reply-To: <3ED4A5E2.32193.DDDB59@localhost> Message-ID: References: <3ED4A5E2.32193.DDDB59@localhost> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=ISO-8859-15 Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from QUOTED-PRINTABLE to 8bit by server.ccl.net id h4SBrCKY009325 Hello Jens and All! On Wed, 28 May 2003, Jens Spanget-Larsen wrote: > Yes, it is true, there has been some discussion on the status of the > MO concept. But to me, there can be no doubt: In principle, orbitals > are one-electron wavefunctions, and for a many-electron system, they > do by definition NOT correspond to physical reality. However, they > are extremely useful models, as we all know. The usefulness of the MO > concept in rationalizing a lot of chemistry and spectroscopy > sometimes leads people to think of MOs as physical quantities, rather > than simplified models. Do you think my point of view is erroneous? I'm not taking sides on which view is more correct, but I am inclined to like the more physical interpretation of orbitals. Even if they for the moment are only mathematical constructs, it doesn't rule out the possibility of a physical foundation to be discovered for them. Orbitals can also, in a sense, be observed experimentally. See for example: [1] Vstrvm et.al., "Orbital rehybridization in n-octane adsorbed on Cu(110)", JCP 118 (2003) 3782-378 [2] Hasselstrvm et.al., J.Phys.Chem B 104 (2000) 11480-11483 Have a nice day, Mikael J. http://www.helsinki.fi/~mpjohans/ From chemistry-request@ccl.net Wed May 28 03:01:30 2003 Received: from luc.ac.be (alpha.luc.ac.be [193.190.2.30]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4S71TKY032400 for ; Wed, 28 May 2003 03:01:30 -0400 Received: from localhost (localhost [127.0.0.1]) by luc.ac.be (8.9.3/8.9.3) with ESMTP id JAA32533; Wed, 28 May 2003 09:01:28 +0200 (MET DST) Received: from 146.49-200-80.adsl.skynet.be (146.49-200-80.adsl.skynet.be [80.200.49.146]) by webmail.luc.ac.be (IMP) with HTTP for ; Wed, 28 May 2003 09:01:23 +0200 Message-ID: <1054105283.3ed45ec36b3f6{at}webmail.luc.ac.be> Date: Wed, 28 May 2003 09:01:23 +0200 From: sergiusz.kwasniewski{at}luc.ac.be To: chemistry{at}ccl.net Cc: chemistry{at}ccl.net Subject: CCL:UV spectrum calculation (new question) References: <000501c3038a$8e52ff40$0300a8c0{at}attbi.com> In-Reply-To: <000501c3038a$8e52ff40$0300a8c0{at}attbi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit User-Agent: Internet Messaging Program (IMP) 3.2.1 Hi, I'm curious how well INDO/S-RPA works against INDO/S-CIS for large systems. I only remember one article by M. Zerner quite a long time ago.. Probably the calculation takes a lot longer (Hamiltonian matrix is four times as big since mixing of particle-hole and hole-particle excitations occurs). About the excitation energies: If I'm not mistaken both CIS and RPA are consistent methods in electron correlation up to 1st order in one-particle excitation energies, but only RPA is up to 1st order for transition dipole moments). Two-particle excitations are not accounted for in CIS, and only partially in RPA, am I right ? Are there any problems with numerical instabilities with the implemented RPA scheme in a INDO/S-RPA calculation ? Serge > > -----Original Message----- > > From: Mark Thompson [mailto:mark{at}planaria-software.com] > > Sent: Tuesday, May 27, 2003 1:47 PM > > To: Jesus Rodriguez-Otero; chemistry{at}ccl.net > > Subject: CCL: UV spectrum calculation > > > > Dear Jesus, > > ZINDO does indeed give good results for large organic systems, mainly those > with low-energy pi-pi* excitations. As with many semi-empirical methods, > it > works best on a series of related molecules where you might be interested > in > the effects of certain substitutents. Also, the effects of solvent can be > very important and several solvent models have been applied to the ZINDO > method with good results. > > Here are a couple of my publications where I applied ZINDO to studies of > photosynthetic pigments: > > "Excited States of the Bacteriochlorophyll b Dimer > of Rhodopseudomonas viridis: A QM/MM Study of the > Photosynthetic Reaction Center That Includes MM > Polarization" J. Phys. Chem. 1995, 99, 6374-6386. > Mark Thompson and Gregory Schenter > > "Effect of a Polarizable Medium on the Charge-Transfer > States of the Photosynthetic Reaction Center from > Rhodopseudomonas viridis. " I. Am. Chem. Soc. > 1990, 112, 7828. Mark Thompson and Michael Zerner > > > ZINDO is available in the ArgusLab 3.1 program. In addition to the normal > ZINDO method (based on singles-CI description of the excited state), > ArgusLab also implements the ZINDO-RPA method which includes contributions > > from certain low-lying doubles and is particularly good at describing > rotational spectra and giving good agreement between dipole length and > dipole velocity transition moments. ArgusLab also implements the > Self-Consistent Reaction Field model of Zerner and Karlsson. > > You can obtain ArgusLab at http:://www.arguslab.com > > Mark Thompson > > ================================= > Mark Thompson, Ph.D. > Planaria Software > PO Box 55207 > Seattle, WA 98155 > > http://www.arguslab.com > FAX: 206-440-3305 > ================================= > > > -= This is automatically added to each message by mailing script =- > To send e-mail to subscribers of CCL put the string CCL: on your Subject: > line > and send your message to: CHEMISTRY{at}ccl.net > > Send your subscription/unsubscription requests to: CHEMISTRY-REQUEST{at}ccl.net > > HOME Page: http://www.ccl.net | Jobs Page: http://www.ccl.net/jobs > > If your mail is bouncing from CCL.NET domain send it to the maintainer: > Jan Labanowski, jkl{at}ccl.net (read about it on CCL Home Page) > -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > > > > From chemistry-request@ccl.net Wed May 28 10:57:56 2003 Received: from sccrmhc02.attbi.com (sccrmhc02.attbi.com [204.127.202.62]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SEvtgC006716 for ; Wed, 28 May 2003 10:57:55 -0400 Received: from c1353359a (12-208-133-89.client.attbi.com[12.208.133.89]) by attbi.com (sccrmhc02) with SMTP id <20030528145754002006d9uee>; Wed, 28 May 2003 14:57:54 +0000 Reply-To: From: "Mark Thompson" To: , Subject: CCL: UV spectrum calculation (new question) Date: Wed, 28 May 2003 07:53:51 -0700 Message-ID: <000301c32528$f3ef1f40$0300a8c0(at)attbi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2911.0) In-Reply-To: <1054105283.3ed45ec36b3f6(at)webmail.luc.ac.be> X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Importance: Normal Dear Serge, > Are there any problems with numerical instabilities with the > implemented RPA scheme in a INDO/S-RPA calculation ? There may be, but to date, we've not had any problems running INDO/S-RPA (aka ZINDO-RPA) on all test systems that we use for standard ZINDO. An exhaustive reparameterization of ZINDO for RPA is not finished. For that matter, an exhaustive parameterization of ZINDO-CIS was also never done, but Mike Zerner and his students over the years managed to generate a fairly useful set of parameters for CIS that do well in most cases. For molecules, like cyclophanes, where low-lying double excitations may be important, then one needs to go beyond CIS with ZINDO. The error for ZINDO-CIS is about 1000 cm^-1 for most systems. ZINDO-RPA appears to descibe excitations better, and generally requires a smaller number of active orbitals in the RPA, relative to CIS. Mark ================================= Mark Thompson, Ph.D. Planaria Software PO Box 55207 Seattle, WA 98155 FAX: 206-440-3305 ArgusLab 3.1 is available at: http://www.arguslab.com ================================= From chemistry-request@ccl.net Wed May 28 10:29:46 2003 Received: from Stud-Mailer.Uni-Marburg.DE (Stud-Mailer.Uni-Marburg.DE [137.248.9.7]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SETjgC005948 for ; Wed, 28 May 2003 10:29:46 -0400 Received: from charly.chemie.uni-marburg.de (pc15160.Chemie.Uni-Marburg.DE [137.248.152.201]) by Stud-Mailer.Uni-Marburg.DE (8.12.8p1/8.12.8) with ESMTP id h4SEOpJr056924 for ; Wed, 28 May 2003 16:24:52 +0200 Subject: Eigenvalues of hessian From: "Daniel R. Rohr" To: ccl Content-Type: text/plain; charset=ISO-8859-1 X-Mailer: Evolution/1.0 (Preview Release) Date: 28 May 2003 16:20:47 +0200 Message-Id: <1054131647.16827.13.camel@charly> Mime-Version: 1.0 X-MailScanner-Information: see http://www.uni-marburg.de/hrz/services/spamcheck/ X-MailScanner: Found to be clean Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by server.ccl.net id h4SETkgC005949 Hi CCLers Does anybody of you know, why there are more than 3N-6 nonzero eigenvalues of the hessian? I am especially interested in the question, whether this error is due to the errors made by differentiation or whether they are due to an error within the method itself. I usually get only 3 zero eigenvalues. No matter if the hessian is calculated on a stationary point or not. Thanks for your help Daniel Rohr -- ----------------------------------------------------------------------- Daniel Rohr Fachbereich Chemie der Philipps-Universitdt Tel.: +49-6421-28-25686 Hans-Meerwein-Stra_e Fax.: +49-6421-28-25566 D-35043 Marburg eMail: rohrd/at/stud-mailer.uni-marburg.de Germany ----------------------------------------------------------------------- From chemistry-request@ccl.net Wed May 28 10:14:43 2003 Received: from mx4.trentu.ca (mx4.trentu.ca [192.75.12.5]) by server.ccl.net (8.12.8/8.12.8) with SMTP id h4SEEhgC005241 for ; Wed, 28 May 2003 10:14:43 -0400 Received: (qmail 25975 invoked by uid 504); 28 May 2003 14:14:42 -0000 Received: from elewars/at/trentu.ca by mx4.trentu.ca by uid 501 with qmail-scanner-1.14 (fsecure: 4.15/4370/2003-05-23/2003-05-23. 2003-05-22/ Clear:. Processed in 0.297787 secs); 28 May 2003 14:14:42 -0000 X-Qmail-Scanner-Mail-From: elewars/at/trentu.ca via mx4.trentu.ca X-Qmail-Scanner: 1.14 (Clear:. Processed in 0.297787 secs) Received: from unknown (HELO trentu.ca) (209.42.101.30) by mx4.trentu.ca with SMTP; 28 May 2003 14:14:42 -0000 Message-ID: <3ED4C513.BD36ECFA/at/trentu.ca> Date: Wed, 28 May 2003 10:17:56 -0400 From: elewars X-Mailer: Mozilla 4.79 [en] (WinNT; U) X-Accept-Language: en MIME-Version: 1.0 To: Jens Spanget-Larsen , chemistry/at/ccl.net Subject: Re: CCL:Orbitals References: <3ED4A5E2.32193.DDDB59@localhost> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit 2003 May 28 Are MOs physically real? This is a meaningful question only if there is some experiment or observation that could provide an answer _yes_ or _no_. Is there, at least in principle, such an experiment or observation? As J S-L points out, MOs are one-electron functions; does this mean that for hydrogenlike atoms they _do_ correspond to physical reality? If MOs have no physical reality for multielectron species, why (a) is Koopmans' theorem useful, why (b) do photoelectron spectra match the predictions of MO energy-level diagrams, and why (c) does the Hueckel 4n+2 rule, which is based on MO diagrams, work? Of course, it is probably possible to formulate an MO-free electronic molecular theory that leads to the same predictions a-c, but I suspect that in some sense (but what sense?) MOs exist--occupied MOs; the meaning of a virtual MO is harder to see. E. Lewars ===== Jens Spanget-Larsen wrote: > Mikael Johansson: > > > On Tue, 27 May 2003, Jens Spanget-Larsen wrote: > > > > > And in principle, MOs are not physical quantities; they are model > > > constructions, and as such they have no physical reality and they > > > cannot be observed experimentally. > > > > Well, there is a lot of discussion in the literature on this topic. > > A few good examples, biased towards my thinking, could be: > > > > [1] Stowasser and Hoffmann, "What Do the Kohn-Sham Orbitals and > > Eigenvalues Mean?", J.Am.Chem.Soc. 121 (1999) 3414-3420. > > [2] Baerends, Theor.Chem.Acc. 103 (2000) 265-269. > > > > Have a nice day, > > Mikael J. > > http://www.helsinki.fi/~mpjohans/ > > Dear Mikael! > > Yes, it is true, there has been some discussion on the status of the > MO concept. But to me, there can be no doubt: In principle, orbitals > are one-electron wavefunctions, and for a many-electron system, they > do by definition NOT correspond to physical reality. However, they > are extremely useful models, as we all know. The usefulness of the MO > concept in rationalizing a lot of chemistry and spectroscopy > sometimes leads people to think of MOs as physical quantities, rather > than simplified models. Do you think my point of view is erroneous? > > Yours, Jens >--< > > ------- End of forwarded message ------- > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= > JENS SPANGET-LARSEN Office: +45 4674 2710 > Department of Chemistry Fax: +45 4674 3011 > Roskilde University (RUC) Mobile: +45 2320 6246 > P.O.Box 260 E-Mail: spanget/at/ruc.dk > DK-4000 Roskilde, Denmark http://virgil.ruc.dk/~spanget > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= > > -= This is automatically added to each message by mailing script =- > To send e-mail to subscribers of CCL put the string CCL: on your Subject: line > and send your message to: CHEMISTRY/at/ccl.net > > Send your subscription/unsubscription requests to: CHEMISTRY-REQUEST/at/ccl.net > HOME Page: http://www.ccl.net | Jobs Page: http://www.ccl.net/jobs > > If your mail is bouncing from CCL.NET domain send it to the maintainer: > Jan Labanowski, jkl/at/ccl.net (read about it on CCL Home Page) > -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ From chemistry-request@ccl.net Wed May 28 10:13:05 2003 Received: from pump2.york.ac.uk (pump2.york.ac.uk [144.32.128.12]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SED4gC005076 for ; Wed, 28 May 2003 10:13:05 -0400 Received: from james.york.ac.uk (james.york.ac.uk [144.32.180.54]) by pump2.york.ac.uk (8.12.9/8.12.9) with ESMTP id h4SED4cU007935 for ; Wed, 28 May 2003 15:13:04 +0100 (BST) Message-Id: <5.2.1.1.0.20030528150904.00b7b488/at/jm45.imap.york.ac.uk> X-Sender: jm45/at/jm45.imap.york.ac.uk X-Mailer: QUALCOMM Windows Eudora Version 5.2.1 Date: Wed, 28 May 2003 15:13:03 +0100 To: chemistry/at/ccl.net From: "Dr. Julia Metzker" Subject: calculating atomic charges with AIMPAC Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed I currently have an undergraduate student who is attempting to compare charges of methylated benzene and ferrocene systems using the AIMPAC software. In the case of hexamethyl benzene and the ferrocene analogues he is getting very large negative charges on some the ring carbons (-5 to -20) and small positive charges on iron (0.5) Can anyone tell me if there is a problem with the program or if the ring system can not be treated with this method? Thank you, Julia Metzker University of York Department of Chemistry From chemistry-request@ccl.net Wed May 28 11:07:55 2003 Received: from smtp2.ruc.dk (smtp2.ruc.dk [130.225.220.70]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SF7sgC007006 for ; Wed, 28 May 2003 11:07:55 -0400 Received: by smtp2.ruc.dk (Postfix, from userid 504) id 2898EC854A1; Wed, 28 May 2003 17:07:54 +0200 (CEST) Received: from virgil.ruc.dk (virgil.ruc.dk [130.225.220.110]) by smtp2.ruc.dk (Postfix) with ESMTP id 352AAC85498 for ; Wed, 28 May 2003 17:07:52 +0200 (CEST) Received: from VIRGIL/SpoolDir by virgil.ruc.dk (Mercury 1.47); 28 May 03 17:07:52 +0100 Received: from SpoolDir by VIRGIL (Mercury 1.47); 28 May 03 17:07:49 +0100 From: "Jens Spanget-Larsen" Organization: Roskilde Universitetscenter To: chemistry$at$ccl.net Date: Wed, 28 May 2003 17:07:23 +0100 Subject: Re: CCL:Orbitals Reply-To: spanget$at$ruc.dk Message-ID: <3ED4DEBC.98.1BBEF37@localhost> X-Confirm-Reading-To: spanget$at$ruc.dk X-pmrqc: 1 Priority: normal In-reply-to: <3ED4C513.BD36ECFA$at$trentu.ca> X-mailer: Pegasus Mail for Windows (v4.01) X-Spam-Status: No, hits=-6.5 required=5.0 tests=IN_REP_TO,QUOTED_EMAIL_TEXT version=2.53 X-Spam-Level: X-Spam-Checker-Version: SpamAssassin 2.53 (1.174.2.15-2003-03-30-exp) E. Lewars: > Are MOs physically real? This is a meaningful question only if there > is some experiment or observation that could provide an answer _yes_ > or _no_. Is there, at least in principle, such an experiment or > observation? I don't agree. For a many-electron system, one-electron wavefunctions are BY DEFINITION physically unreal. They can only be defined by neglecting certain very physical aspects, corresponding to a model where electron correlation effects are neglected. According to basic Physics, real electrons instantaneously correlate their individual movements, but electrons in orbitals don't. Electrons in orbitals are 'quasi-particles', not 'real particles'. > As J S-L points out, MOs are one-electron functions; does this mean > that for hydrogenlike atoms they _do_ correspond to physical reality? For an isolated hydrogen atom, the orbital wavefunctions, using the reduced mass and relativistic quantum mechanics, probably corresponds closely to what one might choose to consider as 'reality'. But in the end, the question becomes entirely philosophical; for example, no-one has ever observed an isolated atom. > If MOs have no physical reality for multielectron species, why (a) is > Koopmans' theorem useful, why (b) do photoelectron spectra match the > predictions of MO energy-level diagrams, and why (c) does the Hueckel > 4n+2 rule, which is based on MO diagrams, work? Of course, it is > probably possible to formulate an MO-free electronic molecular theory > that leads to the same predictions a-c, but I suspect that in some > sense (but what sense?) MOs exist--occupied MOs; the meaning of a > virtual MO is harder to see. The MO concept is very useful, forming the basis for excellent models of chemical and spectroscopic behaviour. For example, if you adopt Koopmans' approximation (neglect of electronic correlation and reorganization effects on ionization), Koopmans' well-known theorem applies. This is frequently a very good model, largely because the different errors introduces by the adoption of Koopmans' approximation tend to cancel each other out. But sometimes Koopmans' approximation is a bad approximation, and Koopmans' theorem does not apply. Or in the other words: The MO picture of ionization is sometimes a good model, and sometimes it is not. In any case: MOs don't exist in the physical sense. But of course, you may say that they 'exist' in our minds! Jens >--< =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= JENS SPANGET-LARSEN Office: +45 4674 2710 Department of Chemistry Fax: +45 4674 3011 Roskilde University (RUC) Mobile: +45 2320 6246 P.O.Box 260 E-Mail: spanget$at$ruc.dk DK-4000 Roskilde, Denmark http://virgil.ruc.dk/~spanget =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= From chemistry-request@ccl.net Wed May 28 11:11:54 2003 Received: from ccl.net (atlantis.ccl.net [192.148.249.4]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SFBsgC007100 for ; Wed, 28 May 2003 11:11:54 -0400 Received: from krakow.ccl.net (krakow.ccl.net [192.148.249.195]) by ccl.net (8.11.6+Sun/8.11.6/OSC 2.1) with ESMTP id h4SFBrt05039; Wed, 28 May 2003 11:11:53 -0400 (EDT) Date: Wed, 28 May 2003 11:11:53 -0400 (EDT) From: Jan Labanowski To: chemistry$at$ccl.net cc: Jan Labanowski Subject: Spam, CCL, and me... Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII The question from subscriber prompted this message to all subscribers. 1) I do understand subscribers concerns that they do not want to post to CCL from their company/university e-mail address. Yes, there are policies, and liabilities involved. Yes, it is much safer to post from you PRIVATE email address. However, there is an advantage to post from company/university address. 2) The reason for posting with the company/university address is that I very reluctantly put them onto a blacklist. That is, you can post from these addresses and your mail will not have "Access denied" bounce. The private accounts like on yahoo.com or hotmail.com, etc., often have problems posting to CCL since the respective domains are on the blacklist (since I get tons of spam from them). 3) You can post to CCL from ANY address on Earth, assuming that the subnet from which you post is not blacklisted. If it is blacklisted (i.e., mail bounces with 'Access denied' from chemistry$at$ccl.net), you need to send your message to me: jkl$at$ccl.net so I resend it. The subscription list is not checked when deciding if message can be posted. Your subscription address is only the address WHERE YOU GET MAIL from CCL. You do not have to use it to POST to CCL. So you can still receive mail to your company address, but post to CCL from your private address, or your friend's private address, whatever it it. 4) As I said, many "free e-mail accounts" will have problem posting, since the providers of such service also provide a opportunity for spammers. Now, if your mail from the private address bounces from CCL, send it to jkl$at$ccl.net (I do not have a blacklist attached to this address, to my demise and despair) and I will resend message to CCL for you. 5) Read the bottom of the messages you receive from CCL. For example, when you post to CCL, put the four letter word, CCL:, somewhere on the Subject line. It will prevent your message to go to unconditional manual review (it may well still end up there if you use some words which are often found in spam messages or some other things in your message may be "suspisious" to the CCL scripts). Please understand that CCL gets about 1000 spam messages a day. You see only one in a month or less, on average, but it happens because I work on the principle 'better safe than sorry'. Of course, once you have to screen mail manually or automatically, it will cause delays and often human errors. Oh well... There are people out there who screwed it up for all of us... We need a new e-mail standard which authenticates the sender of mail. I will gladly receive all my spam, if they pay me a $1 per each message. I would be a millionaire by now... Jan K. Labanowski | phone: 614-292-9279, FAX: 614-292-7168 Ohio Supercomputer Center | E-mail: jkl$at$ccl.net 1224 Kinnear Rd, | http://www.ccl.net/~jkl Columbus, OH 43212-1163 | http://www.ccl.net/ http://asdn.net/ From chemistry-request@ccl.net Wed May 28 11:34:01 2003 Received: from uni-kl.de (mail.uni-kl.de [131.246.137.52]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SFY0gC007981 for ; Wed, 28 May 2003 11:34:00 -0400 Received: from mailgate1.uni-kl.de (mailgate1.uni-kl.de [131.246.120.5]) by uni-kl.de (8.12.8/8.12.8) with ESMTP id h4SFXxHt019886 for ; Wed, 28 May 2003 17:33:59 +0200 (MET DST) Received: from service.chemie.uni-kl.de (service.chemie.uni-kl.de [131.246.58.77]) by mailgate1.uni-kl.de (8.12.7/8.12.7) with ESMTP id h4SFXxP5003291 for ; Wed, 28 May 2003 17:33:59 +0200 Received: from localhost (localhost [127.0.0.1]) by service.chemie.uni-kl.de (Postfix) with ESMTP id 8CB9836CFE for ; Wed, 28 May 2003 17:32:54 +0200 (CEST) Received: from pc1.chemie.uni-kl.de (pc1.chemie.uni-kl.de [131.246.58.1]) by service.chemie.uni-kl.de (Postfix) with ESMTP id B011336CFD for ; Wed, 28 May 2003 17:32:53 +0200 (CEST) Received: from pc3 (pc3.chemie.uni-kl.de [131.246.58.3]) by pc1.chemie.uni-kl.de (Postfix) with ESMTP id 398F413CAE for ; Wed, 28 May 2003 17:33:58 +0200 (CEST) Content-Type: text/plain; charset="iso-8859-1" From: Elmar Gerwalin Reply-To: elg-.at.-chemie.uni-kl.de To: chemistry-.at.-ccl.net Subject: Re: CCL:Spam, CCL, and me... Date: Wed, 28 May 2003 17:33:57 +0200 User-Agent: KMail/1.4.3 References: In-Reply-To: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-Id: <200305281733.57663.elg-.at.-chemie.uni-kl.de> X-Virus-Scanned: by AMaViS 0.3.12pre8 Hello ! Would'n it be a good idea to convert the CCL Mailing list to a newsgroup ? Maybe this would have other disadvantages, but bringing much advantages, too: Sorted threads, moderation, reading by web interface, ... Bye Elmar On Wednesday 28 May 2003 17:11, Jan Labanowski wrote: > The question from subscriber prompted this message to all subscribers. > > 1) I do understand subscribers concerns that they do not want to post to > CCL from their company/university e-mail address. Yes, there are > policies, and liabilities involved. Yes, it is much safer to post from you > PRIVATE email address. However, there is an advantage to post from > company/university address. > > 2) The reason for posting with the company/university address is that > I very reluctantly put them onto a blacklist. That is, you can post from > these addresses and your mail will not have "Access denied" bounce. > The private accounts like on yahoo.com or hotmail.com, etc., often > have problems posting to CCL since the respective domains are on > the blacklist (since I get tons of spam from them). > > 3) You can post to CCL from ANY address on Earth, assuming that the subnet > from which you post is not blacklisted. If it is blacklisted (i.e., > mail bounces with 'Access denied' from chemistry-.at.-ccl.net), you need > to send your message to me: jkl-.at.-ccl.net so I resend it. The subscription > list is not checked when deciding if message can be posted. Your > subscription address is only the address WHERE YOU GET MAIL from CCL. > You do not have to use it to POST to CCL. So you can still receive mail > to your company address, but post to CCL from your private address, or your > friend's private address, whatever it it. > > 4) As I said, many "free e-mail accounts" will have problem posting, since > the providers of such service also provide a opportunity for spammers. > Now, if your mail from the private address bounces from CCL, send it to > jkl-.at.-ccl.net (I do not have a blacklist attached to this address, to my > demise and despair) and I will resend message to CCL for you. > > 5) Read the bottom of the messages you receive from CCL. For example, > when you post to CCL, put the four letter word, CCL:, somewhere on > the Subject line. It will prevent your message to go to unconditional > manual review (it may well still end up there if you use some words > which are often found in spam messages or some other things in your message > may be "suspisious" to the CCL scripts). > > Please understand that CCL gets about 1000 spam messages a day. > You see only one in a month or less, on average, but it happens because > I work on the principle 'better safe than sorry'. Of course, > once you have to screen mail manually or automatically, it will > cause delays and often human errors. Oh well... There are people out > there who screwed it up for all of us... We need a new e-mail standard > which authenticates the sender of mail. I will gladly receive all my > spam, if they pay me a $1 per each message. I would be a millionaire by > now... > > > Jan K. Labanowski | phone: 614-292-9279, FAX: 614-292-7168 > Ohio Supercomputer Center | E-mail: jkl-.at.-ccl.net > 1224 Kinnear Rd, | http://www.ccl.net/~jkl > Columbus, OH 43212-1163 | http://www.ccl.net/ http://asdn.net/ > > > > -= This is automatically added to each message by mailing script =- > To send e-mail to subscribers of CCL put the string CCL: on your Subject: > line and send your message to: CHEMISTRY-.at.-ccl.net > > Send your subscription/unsubscription requests to: > CHEMISTRY-REQUEST-.at.-ccl.net HOME Page: http://www.ccl.net | Jobs Page: > http://www.ccl.net/jobs > > If your mail is bouncing from CCL.NET domain send it to the maintainer: > Jan Labanowski, jkl-.at.-ccl.net (read about it on CCL Home Page) > -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -- ======================================================== Elmar Gerwalin , University of Kaiserslautern,Germany Dept. of Theoretical Chemistry and IT Service Team elg-.at.-chemie.uni-kl.de 0631-205-2749 ======================================================== From chemistry-request@ccl.net Wed May 28 12:31:28 2003 Received: from exmails1.chem.ucla.edu (d-169-232-134-2.chem.ucla.edu [169.232.134.2]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SGVRgC010912 for ; Wed, 28 May 2003 12:31:27 -0400 Received: from [128.97.147.222] (ch-22.psnet.ucla.edu [128.97.147.222]) (authenticated bits=0) by exmails1.chem.ucla.edu (8.12.8/8.12.8) with ESMTP id h4SGVO7s030561 for ; Wed, 28 May 2003 09:31:26 -0700 Mime-Version: 1.0 X-Sender: scerri.-at-.chlorine.chem.ucla.edu (Unverified) Message-Id: Date: Wed, 28 May 2003 09:30:51 -0700 To: ccl From: Eric Scerri Subject: orbitals Content-Type: text/plain; charset="us-ascii" ; format="flowed" It seems to me that paper [1] at least makes the elementary philosophical error of claiming that if something is useful then it must have physical reality. Stowasser and Hoffmann say virtually as much in this article. Many scientific concepts have proved useful in the history of science but were eventually found to be redundant or non-existent. For example, caloric, phlogiston, the ether etc. But is there a sense in which the Kohn-Sham orbitals are "more real" than the orbitals used in ab initio work? This seems to be the claim of some recent authors. But then we get into another odd notion, namely that having physical reality comes in degrees! please see, The Recently Claimed Observation of Atomic Orbitals and Some Related Philosophical Issues", Philosophy of Science, 68,(Proceedings) S76-S88, N. Koertge, ed. Philosophy of Science Association, East Lansing, MI, (2001) Have Orbitals Really Been Observed?, Journal of Chemical Education, 77, 1492-1494, (2000) although neither of these articles discuss the reality of orbitals of the DFT variety. regards, eric scerri I would like to invite contibutions of articles or comments on this question to the journal Foundations of Chemistry (see below for info). ---------- > On Tue, 27 May 2003, Jens Spanget-Larsen wrote: >> >> > And in principle, MOs are not physical quantities; they are model >> > constructions, and as such they have no physical reality and they >> > cannot be observed experimentally. >> >> Well, there is a lot of discussion in the literature on this topic. >> A few good examples, biased towards my thinking, could be: >> >> [1] Stowasser and Hoffmann, "What Do the Kohn-Sham Orbitals and >> Eigenvalues Mean?", J.Am.Chem.Soc. 121 (1999) 3414-3420. >> [2] Baerends, Theor.Chem.Acc. 103 (2000) 265-269. > -- Dr. Eric Scerri , UCLA, Department of Chemistry & Biochemistry, 607 Charles E. Young Drive East, Los Angeles, CA 90095-1569 USA E-mail : scerri.-at-.chem.ucla.edu tel: 310 206 7443 fax: 310 206 2061 Web Page: http://www.chem.ucla.edu/dept/Faculty/scerri/index.html Editor of Foundations of Chemistry http://www.kluweronline.com/issn/1386-4238 Also see International Society for the Philosophy of Chemistry http://www.georgetown.edu/earleyj/ISPC.html From chemistry-request@ccl.net Wed May 28 13:42:45 2003 Received: from carbon.chem.ucla.edu ([128.97.35.55]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SHgigC012183 for ; Wed, 28 May 2003 13:42:45 -0400 Received: from chem.ucla.edu (dserv2.chem.ucla.edu [169.232.135.19]) by carbon.chem.ucla.edu (8.12.8/8.12.8) with SMTP id h4SHgdN5020870; Wed, 28 May 2003 10:42:39 -0700 (PDT) Message-Id: <200305281742.h4SHgdN5020870.-at-.carbon.chem.ucla.edu> Date: Wed, 28 May 2003 17:42:39 -0000 To: "Daniel R. Rohr" , "ccl" Subject: Re: CCL:Eigenvalues of hessian From: "Amity Andersen" X-Mailer: TWIG 2.7.5 In-Reply-To: <1054131647.16827.13.camel@charly> Is your system linear? "Daniel R. Rohr" said: > Hi CCLers > > Does anybody of you know, why there are more than 3N-6 nonzero > eigenvalues of the hessian? I am especially interested in the question, > whether this error is due to the errors made by differentiation or > whether they are due to an error within the method itself. I usually get > only 3 zero eigenvalues. No matter if the hessian is calculated on a > stationary point or not. > > Thanks for your help > > Daniel Rohr > > -- > ----------------------------------------------------------------------- > Daniel Rohr Fachbereich Chemie der > Philipps-Universitdt > Tel.: +49-6421-28-25686 Hans-Meerwein-Stra_e > Fax.: +49-6421-28-25566 D-35043 Marburg > eMail: rohrd.-at-.stud-mailer.uni-marburg.de Germany > ----------------------------------------------------------------------- > > > > > -= This is automatically added to each message by mailing script =- > To send e-mail to subscribers of CCL put the string CCL: on your Subject: line > and send your message to: CHEMISTRY.-at-.ccl.net > > Send your subscription/unsubscription requests to: CHEMISTRY-REQUEST.-at-.ccl.net > HOME Page: http://www.ccl.net | Jobs Page: http://www.ccl.net/jobs > > If your mail is bouncing from CCL.NET domain send it to the maintainer: > Jan Labanowski, jkl.-at-.ccl.net (read about it on CCL Home Page) > -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > > > > -- Amity Andersen UCLA Dept. of Chemistry & Biochemistry Room: 3051 Young Hall (310) 206-5931 andersen.-at-.chem.ucla.edu From chemistry-request@ccl.net Wed May 28 11:36:50 2003 Received: from kelly.bath.ac.uk (kelly.bath.ac.uk [138.38.32.20]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SFangC008053 for ; Wed, 28 May 2003 11:36:50 -0400 Received: from midge.bath.ac.uk ([138.38.32.34] ident=mmdf) by kelly.bath.ac.uk with smtp id 19L2yu-0006nm-6R; Wed, 28 May 2003 16:36:48 +0100 Received: from prpcn144 ( prpc-n144.bath.ac.uk [138.38.128.144] ) by bath.ac.uk id aa16287 ; 28 May 2003 16:36 +0100 From: James Robinson To: "Daniel R. Rohr" , ccl Subject: RE: Eigenvalues of hessian Date: Wed, 28 May 2003 16:37:04 +0100 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2911.0) X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 Importance: Normal In-Reply-To: <1054131647.16827.13.camel@charly> X-Scanner: *19L2yu-0006nm-6R*hmabWlK1Neg* Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by server.ccl.net id h4SFaogC008056 Some numerical methods use small perturbations in the x, y and z planes to compute force constants. Unfortunately this effectively contaminates the calculation with net translations. Could this be happening in your Hessian calc? James (if I wrong, do let me know!) -----Original Message----- From: Computational Chemistry List [mailto:chemistry-request.-at-.ccl.net]On Behalf Of Daniel R. Rohr Sent: 28 May 2003 15:21 To: ccl Subject: CCL:Eigenvalues of hessian Hi CCLers Does anybody of you know, why there are more than 3N-6 nonzero eigenvalues of the hessian? I am especially interested in the question, whether this error is due to the errors made by differentiation or whether they are due to an error within the method itself. I usually get only 3 zero eigenvalues. No matter if the hessian is calculated on a stationary point or not. Thanks for your help Daniel Rohr -- ----------------------------------------------------------------------- Daniel Rohr Fachbereich Chemie der Philipps-Universitdt Tel.: +49-6421-28-25686 Hans-Meerwein-Stra_e Fax.: +49-6421-28-25566 D-35043 Marburg eMail: rohrd.-at-.stud-mailer.uni-marburg.de Germany ----------------------------------------------------------------------- -= This is automatically added to each message by mailing script =- To send e-mail to subscribers of CCL put the string CCL: on your Subject: line and send your message to: CHEMISTRY.-at-.ccl.net Send your subscription/unsubscription requests to: CHEMISTRY-REQUEST.-at-.ccl.net HOME Page: http://www.ccl.net | Jobs Page: http://www.ccl.net/jobs If your mail is bouncing from CCL.NET domain send it to the maintainer: Jan Labanowski, jkl.-at-.ccl.net (read about it on CCL Home Page) -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ From chemistry-request@ccl.net Wed May 28 12:46:15 2003 Received: from web10410.mail.yahoo.com (web10410.mail.yahoo.com [216.136.128.123]) by server.ccl.net (8.12.8/8.12.8) with SMTP id h4SGkEgC011229 for ; Wed, 28 May 2003 12:46:15 -0400 Message-ID: <20030528164614.5452.qmail.-at-.web10410.mail.yahoo.com> Received: from [40.0.40.10] by web10410.mail.yahoo.com via HTTP; Wed, 28 May 2003 09:46:14 PDT Date: Wed, 28 May 2003 09:46:14 -0700 (PDT) From: Guosheng Wu Subject: Re: CCL:Orbitals To: chemistry.-at-.ccl.net MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii > > > --- elewars wrote: > > > > 2003 May 28 > > > > > > > > Are MOs physically real? This is a meaningful question only if there is some > > > > experiment or observation that could provide an answer _yes_ or _no_. Is there, > > > > at least in principle, such an experiment or observation? > > Guosheng Wu wrote: > > > > > MO is just a useful mathematical tool for quantum chemistry/physics, and > > > it seems to me itself does not have much physical meaning. > > > > > > However, many properties from MOs are meaningful and can be observed > > > by exmperiments: such as the square of absolute MOs (|MO|^2) corresponding > > > to the electronic density. Things like |MO|^2 of d-orbitals were published > > > in a Science article last one or a few years. > --- elewars wrote: > > Hello, > > > > Thanks for your ideas. If photoel. spectra (and Koopmans theorem--in this case the > > second MO is at the ionization limit) really measure the energy difference of two MOs, > > then MOs exist! > > > > In any case, it is an interesting discussion. > > > > EL > > ===== The properties from |MO|^2 exist does not really mean MO exists. When we know some properties from x^2 exist and can be measured, this does not mean x exists and can be measured. For example, what does the complex number(i) mean in the real world? Measurable? Not really, but obviously it's a useful mathematical tool for lots of applications. Certainly (i^2=-1) means something. Right? Related issue for absolute energy: energy difference is measurable by many kind of experiments, but not for the absolute energy. This may lead to some kind of philosophical problem, if one has such a taste. Guosheng __________________________________ Do you Yahoo!? Yahoo! Calendar - Free online calendar with sync to Outlook(TM). http://calendar.yahoo.com From chemistry-request@ccl.net Wed May 28 14:24:53 2003 Received: from smtp.csc.fi (smtp.csc.fi [193.166.0.106]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SIOqgC013666 for ; Wed, 28 May 2003 14:24:52 -0400 Received: from ISOSIRRI (rhols63.adsl.netsonic.fi [194.29.198.63]) by smtp.csc.fi (CSC-Sendmail) with ESMTP id h4SIOhdT021680 for ; Wed, 28 May 2003 21:24:44 +0300 From: "Leif Laaksonen" To: Subject: CCL: RE: Orbitals Date: Wed, 28 May 2003 21:24:41 +0300 Message-ID: <003801c32546$68145fd0$bb1c7b0a@ISOSIRRI> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.4510 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 Importance: Normal In-Reply-To: <20030528164614.5452.qmail_at_web10410.mail.yahoo.com> X-Scanned-By: MIMEDefang 2.31 (www . roaringpenguin . com / mimedefang) Hi, I might remember wrong from my primary courses in quantum chemistry that only obsrvables are the expectation values from the wave function! This means that while the wave function (|P>) as such is not observable the expectation value of property X is (). Regards, -leif -----Original Message----- From: Computational Chemistry List [mailto:chemistry-request_at_ccl.net] On Behalf Of Guosheng Wu Sent: Wednesday, May 28, 2003 7:46 PM To: chemistry_at_ccl.net Subject: CCL:Orbitals > > > --- elewars wrote: > > > > 2003 May 28 > > > > > > > > Are MOs physically real? This is a meaningful question only if there is some > > > > experiment or observation that could provide an answer _yes_ or _no_. Is there, > > > > at least in principle, such an experiment or observation? > > Guosheng Wu wrote: > > > > > MO is just a useful mathematical tool for quantum chemistry/physics, and > > > it seems to me itself does not have much physical meaning. > > > > > > However, many properties from MOs are meaningful and can be observed > > > by exmperiments: such as the square of absolute MOs (|MO|^2) corresponding > > > to the electronic density. Things like |MO|^2 of d-orbitals were published > > > in a Science article last one or a few years. > --- elewars wrote: > > Hello, > > > > Thanks for your ideas. If photoel. spectra (and Koopmans theorem--in this case the > > second MO is at the ionization limit) really measure the energy difference of two MOs, > > then MOs exist! > > > > In any case, it is an interesting discussion. > > > > EL > > ===== The properties from |MO|^2 exist does not really mean MO exists. When we know some properties from x^2 exist and can be measured, this does not mean x exists and can be measured. For example, what does the complex number(i) mean in the real world? Measurable? Not really, but obviously it's a useful mathematical tool for lots of applications. Certainly (i^2=-1) means something. Right? Related issue for absolute energy: energy difference is measurable by many kind of experiments, but not for the absolute energy. This may lead to some kind of philosophical problem, if one has such a taste. Guosheng __________________________________ Do you Yahoo!? Yahoo! Calendar - Free online calendar with sync to Outlook(TM). http://calendar.yahoo.com -= This is automatically added to each message by mailing script =- To send e-mail to subscribers of CCL put the string CCL: on your Subject: line and send your message to: CHEMISTRY_at_ccl.net Send your subscription/unsubscription requests to: CHEMISTRY-REQUEST_at_ccl.net HOME Page: http://www.ccl.net | Jobs Page: http://www.ccl.net/jobs If your mail is bouncing from CCL.NET domain send it to the maintainer: Jan Labanowski, jkl_at_ccl.net (read about it on CCL Home Page) -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ From chemistry-request@ccl.net Wed May 28 13:50:56 2003 Received: from bast.u.arizona.edu (bast.U.Arizona.EDU [128.196.133.225]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SHosgC012722 for ; Wed, 28 May 2003 13:50:54 -0400 Received: from localhost (mcafiero@localhost) by bast.u.arizona.edu (8.11.7+Sun/8.10.2) with ESMTP id h4SHomm21690; Wed, 28 May 2003 10:50:48 -0700 (MST) X-Authentication-Warning: bast.u.arizona.edu: mcafiero owned process doing -bs Date: Wed, 28 May 2003 10:50:48 -0700 (MST) From: Mauricio L Cafiero To: elewars cc: Jens Spanget-Larsen , Subject: CCL:Orbitals In-Reply-To: <3ED4C513.BD36ECFA:at:trentu.ca> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII hello: If we take quantum mechanics to be valid, and we accept that the two particle coulomb interaction is the predominant potential energy term in the hamitonian, then MO's are physically meaningless. They are simply artifacts of approximations, a zero-order wavefunction. QM could have evolved completely without orbitals (except for H-atom of course). I think the reason we jumped on orbitals so early in history is that they are a fantastic approximation and that orthogonal orbitals save a lot of time computationally. It is the very excellence of the orbital approximation that makes orbitals out to be more than they are. As was said before, they are conceptually easy to grasp. As far a Koopmans', it makes no explicilt reference to orbitals. It is simply that the orbital energy is what remains when you subtract the energies of the two wave functions in the single determinant approximation. I also have to say that PES does not always agree well with orbital diagrams, at least not quantitatively. Mauricio Cafiero Postdoctoral Research Associate Computational Chemistry Team National Institute of Standards and Technology Gaithersburg, Maryland From chemistry-request@ccl.net Wed May 28 13:49:51 2003 Received: from puck.reed.edu (puck.reed.edu [134.10.2.8]) by server.ccl.net (8.12.8/8.12.8) with SMTP id h4SHnpgC012697 for ; Wed, 28 May 2003 13:49:51 -0400 Received: (qmail 14818 invoked from network); 28 May 2003 17:49:49 -0000 Received: from rosencrantz.reed.edu (134.10.2.31) by puck.reed.edu with SMTP; 28 May 2003 17:49:49 -0000 Message-id: <14138338:at:rosencrantz.reed.edu> Date: 28 May 2003 10:49:48 PDT From: Alan.Shusterman:at:directory.reed.edu (Alan Shusterman) Subject: CCL: Orbitals To: chemistry:at:ccl.net MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by server.ccl.net id h4SHnqgC012698 Some of the postings on this subject have cited *correlations* between orbital properties and physical observables as evidence that orbitals "in some sense" exist. example: If MOs have no physical reality for multielectron species, why (a) is Koopmans' theorem useful, why (b) do photoelectron spectra match the predictions of MO energy-level diagrams, and why (c) does the Hueckel 4n+2 rule, which is based on MO diagrams, work? (E. Lewars) example: Orbitals can also, in a sense, be observed experimentally. (M. Johansson) I'm sympathetic to these statements, but I prefer Jens' point of view. I am writing not to cast my vote, but to point out an interesting (to me, anyway) parallel. I teach organic chemistry every fall semester, and every year I must convince my students that *resonance contributors* do not exist even though one can correlate physical observables with the properties of these contributors. Some may still insist that, "if we routinely think of object X to make a prediction, then object X exists, at least in our minds". This is an interesting idea, but I don't think that it relates well to "existence" in the way chemists use this word. I'd like to thank everyone who has contributed to this discussion so far. It has been interesting. -Alan ==== Alan Shusterman Department of Chemistry Reed College Portland, OR academic.reed.edu/chemistry/alan/ From chemistry-request@ccl.net Wed May 28 14:41:55 2003 Received: from SEMOVM.SEMO.EDU (semovm.semo.edu [150.201.1.1]) by server.ccl.net (8.12.8/8.12.8) with SMTP id h4SIftgC014104 for ; Wed, 28 May 2003 14:41:55 -0400 Received: from DUBEN.semovm.semo.edu [150.201.127.221] by SEMOVM.SEMO.EDU (IBM VM SMTP Level 310) via TCP with SMTP ; Wed, 28 May 2003 13:42:14 CDT Message-Id: <5.1.0.14.0.20030528133927.00b2e270{at}semovm.semo.edu> X-Sender: ajduben{at}semovm.semo.edu X-Mailer: QUALCOMM Windows Eudora Version 5.1 Date: Wed, 28 May 2003 13:41:25 -0500 To: Chemistry{at}ccl.net From: Anthony Duben Subject: CCL:Spam, CCL, and me... In-Reply-To: <200305281733.57663.elg{at}chemie.uni-kl.de> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed This would not be helpful at all if one is at an institution lacking decent newsgroup access. E-mail is a much more generally available to a wide variety of subscribers. AJD At 05:33 PM 5/28/2003 +0200, you wrote: >Hello ! > >Would'n it be a good idea to convert the CCL Mailing list to a newsgroup ? > >Maybe this would have other disadvantages, but bringing much advantages, too: > >Sorted threads, moderation, reading by web interface, ... > >Bye >Elmar > Anthony J. Duben Professor and Chairman Computer Science Department Mail Stop 5950 Southeast Missouri State University 1 University Plaza Cape Girardeau MO 63701-4799 phone: 573-651-2194 fax: 573-651-2791\ e-mail: ajduben{at}semo.edu "When life is very bad, two things make life worth living: Mozart and quantum mechanics." -- Victor Weisskopf From chemistry-request@ccl.net Wed May 28 14:45:39 2003 Received: from mail.uvigo.es (mail.uvigo.es [193.146.32.91]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SIjcgC014186 for ; Wed, 28 May 2003 14:45:38 -0400 Received: from mail.uvigo.es (localhost [127.0.0.1]) by mail.uvigo.es (8.12.9/8.12.1) with ESMTP id h4SIjb4m018377 for ; Wed, 28 May 2003 20:45:37 +0200 Received: from correo.uvigo.es (correo.uvigo.es [193.146.32.68]) by mail.uvigo.es (8.12.9/8.12.1) with ESMTP id h4SIjbZk018371 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NOT) for ; Wed, 28 May 2003 20:45:37 +0200 Received: from correo (correo [193.146.32.68]) by correo.uvigo.es (8.12.9/8.12.5) with ESMTP id h4SIjbR5012580; Wed, 28 May 2003 20:45:37 +0200 Date: Wed, 28 May 2003 20:45:37 +0200 (CEST) From: Carlos Silva Lopez X-X-Sender: To: "Dr. Julia Metzker" cc: Subject: Re: CCL:calculating atomic charges with AIMPAC In-Reply-To: <5.2.1.1.0.20030528150904.00b7b488{at}jm45.imap.york.ac.uk> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from QUOTED-PRINTABLE to 8bit by server.ccl.net id h4SIjdgC014187 Hello, Though I do not know which method you are using to get the wavefunction, I would blame first to the quality of the wavefunction than to the aimpac program. Check the boundaries of the carbon atoms to see if the atomic basin is what you expect to be. Hope it helps _-_-_-_-_-_-_-_-_-_-_-_- Carlos Silva Lspez Dept. Qummica Organica Universidade de Vigo Phone:0034 986812226 -_-_-_-_-_-_-_-_-_-_-_-_ From chemistry-request@ccl.net Wed May 28 15:11:05 2003 Received: from mx4.trentu.ca (mx4.trentu.ca [192.75.12.5]) by server.ccl.net (8.12.8/8.12.8) with SMTP id h4SJB4gC014837 for ; Wed, 28 May 2003 15:11:04 -0400 Received: (qmail 17445 invoked by uid 504); 28 May 2003 19:11:04 -0000 Received: from elewars_at_trentu.ca by mx4.trentu.ca by uid 501 with qmail-scanner-1.14 (fsecure: 4.15/4370/2003-05-23/2003-05-23. 2003-05-22/ Clear:. Processed in 0.320058 secs); 28 May 2003 19:11:04 -0000 X-Qmail-Scanner-Mail-From: elewars_at_trentu.ca via mx4.trentu.ca X-Qmail-Scanner: 1.14 (Clear:. Processed in 0.320058 secs) Received: from unknown (HELO trentu.ca) (209.42.101.30) by mx4.trentu.ca with SMTP; 28 May 2003 19:11:03 -0000 Message-ID: <3ED50A89.BEE51E1F_at_trentu.ca> Date: Wed, 28 May 2003 15:14:17 -0400 From: elewars X-Mailer: Mozilla 4.79 [en] (WinNT; U) X-Accept-Language: en MIME-Version: 1.0 To: Jens Spanget-Larsen , chemistry_at_ccl.net, mparnis_at_trentu.ca Subject: Re: CCL:Orbitals References: <3ED4DEBC.98.1BBEF37@localhost> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit 2003 May 28 Hello, Good points! Especially the idea that MOs are unreal _by definition_. If you insist that an MO must be a one-electron function (I know this is in the usual definition) then I suppose it could be "real" only for a hydrogenlike atom. For these, as you imply, the exact solutions of the Schroedinger equation evidently are physically real. As for the point about observing an isolated system--Heisenberg and Platonic reality....that could lead one far afield, perhaps. EL ================== Jens Spanget-Larsen wrote: > E. Lewars: > > > Are MOs physically real? This is a meaningful question only if there > > is some experiment or observation that could provide an answer _yes_ > > or _no_. Is there, at least in principle, such an experiment or > > observation? > > I don't agree. For a many-electron system, one-electron wavefunctions > are BY DEFINITION physically unreal. They can only be defined by > neglecting certain very physical aspects, corresponding to a model > where electron correlation effects are neglected. According to basic > Physics, real electrons instantaneously correlate their individual > movements, but electrons in orbitals don't. Electrons in orbitals are > 'quasi-particles', not 'real particles'. > > > As J S-L points out, MOs are one-electron functions; does this mean > > that for hydrogenlike atoms they _do_ correspond to physical reality? > > For an isolated hydrogen atom, the orbital wavefunctions, using the > reduced mass and relativistic quantum mechanics, probably corresponds > closely to what one might choose to consider as 'reality'. But in the > end, the question becomes entirely philosophical; for example, no-one > has ever observed an isolated atom. > > > If MOs have no physical reality for multielectron species, why (a) is > > Koopmans' theorem useful, why (b) do photoelectron spectra match the > > predictions of MO energy-level diagrams, and why (c) does the Hueckel > > 4n+2 rule, which is based on MO diagrams, work? Of course, it is > > probably possible to formulate an MO-free electronic molecular theory > > that leads to the same predictions a-c, but I suspect that in some > > sense (but what sense?) MOs exist--occupied MOs; the meaning of a > > virtual MO is harder to see. > > The MO concept is very useful, forming the basis for excellent models > of chemical and spectroscopic behaviour. For example, if you adopt > Koopmans' approximation (neglect of electronic correlation and > reorganization effects on ionization), Koopmans' well-known theorem > applies. This is frequently a very good model, largely because the > different errors introduces by the adoption of Koopmans' > approximation tend to cancel each other out. But sometimes Koopmans' > approximation is a bad approximation, and Koopmans' theorem does not > apply. Or in the other words: The MO picture of ionization is > sometimes a good model, and sometimes it is not. > > In any case: MOs don't exist in the physical sense. But of course, > you may say that they 'exist' in our minds! > > Jens >--< > > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= > JENS SPANGET-LARSEN Office: +45 4674 2710 > Department of Chemistry Fax: +45 4674 3011 > Roskilde University (RUC) Mobile: +45 2320 6246 > P.O.Box 260 E-Mail: spanget_at_ruc.dk > DK-4000 Roskilde, Denmark http://virgil.ruc.dk/~spanget > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= > > -= This is automatically added to each message by mailing script =- > To send e-mail to subscribers of CCL put the string CCL: on your Subject: line > and send your message to: CHEMISTRY_at_ccl.net > > Send your subscription/unsubscription requests to: CHEMISTRY-REQUEST_at_ccl.net > HOME Page: http://www.ccl.net | Jobs Page: http://www.ccl.net/jobs > > If your mail is bouncing from CCL.NET domain send it to the maintainer: > Jan Labanowski, jkl_at_ccl.net (read about it on CCL Home Page) > -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ From chemistry-request@ccl.net Wed May 28 16:23:38 2003 Received: from smtp1.uh.cu (smtp1.uh.cu [200.55.139.212]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SKNTgC016726 for ; Wed, 28 May 2003 16:23:35 -0400 Received: from localhost (localhost.localdomain [127.0.0.1]) by smtp1.uh.cu (Postfix) with ESMTP id D6F0C34F8A for ; Wed, 28 May 2003 16:22:37 -0400 (CDT) Received: from fq.uh.cu (canaria.qct.fq.oc.uh.cu [192.168.3.4]) by smtp1.uh.cu (Postfix) with ESMTP id AD52A34F89 for ; Wed, 28 May 2003 16:22:37 -0400 (CDT) Received: from Yigni (espectro.qct.fq.oc.uh.cu [192.168.3.44]) by fq.uh.cu (8.9.0/8.8.7) with SMTP id PAA20974 for ; Wed, 28 May 2003 15:30:21 -0400 Message-Id: <200305281930.PAA20974.-at-.fq.uh.cu> From: "=?ISO-8859-1?Q?Reynier_Suardiaz_del_R=EDo?=" To: chemistry.-at-.ccl.net Date: Thu, 28 May 1998 16:21:09 +0000 MIME-Version: 1.0 Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7BIT Subject: giao method Priority: normal X-mailer: Pegasus Mail for Windows (v3.01d) X-Virus-Scanned: by AMaViS snapshot-20020300 I need to know about the GIAO method' theory to calculate chemical shifts in NMR. Does anybody know a site or a paper or whatever about this theme that can help me? Thanks, Reynier. From chemistry-request@ccl.net Wed May 28 16:11:16 2003 Received: from srvus010.unitedcatalysts.com (srvus010.unitedcatalysts.com [208.23.162.8] (may be forged)) by server.ccl.net (8.12.8/8.12.8) with SMTP id h4SKBGgC016346 for ; Wed, 28 May 2003 16:11:16 -0400 Received: by lvlxch02.ntdomain.americas.sc-world.com with Internet Mail Service (5.5.2653.19) id ; Wed, 28 May 2003 16:09:12 -0400 Message-ID: <5CF08BBFE6DE97478C1E76E654CAF90801BC0BEC.-at-.lvlxch02.ntdomain.americas.sc-world.com> From: "Shobe, Dave" To: chemistry.-at-.ccl.net Subject: CCL: RE: Orbitals Date: Wed, 28 May 2003 16:09:12 -0400 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2653.19) Content-Type: multipart/mixed; boundary="----=_NextPartTM-000-67f96a30-3d23-4b14-834c-ca372b14676f" This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. ------=_NextPartTM-000-67f96a30-3d23-4b14-834c-ca372b14676f Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01C32555.0155E480" ------_=_NextPart_001_01C32555.0155E480 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable This may only show that my mind is *Really* contaminated by the calculational methods, but I tend to think of the orbitals as the mathematical building blocks out of which the wave function is = constructed, as a linear combination of the determinants thereof. A multi-electron = wave function is just too complicated to comprehend in its entirety. =20 But (I think this is true) if you include the contributions of all determinants made from the entire set of orbitals--i.e. full CI with no approximations--the orbitals are not unique and any set of orbitals = that "spans the vector space," as a mathematician would put it, can be used. --David Shobe S=FCd-Chemie Inc. phone (502) 634-7409 fax (502) 634-7724 email dshobe.-at-.sud-chemieinc.com Don't bother flaming me: I'm behind a firewall. P.S. I wonder if one could define the HOMO at least by reversing = Koopman's theorem and calculating the HOMO from the electron density difference between the molecule and its "vertical" radical cation. And similarly = with the LUMO using the vertical radical anion, if it exists. Or does one necessarily run into Guosheng Wu's paradox of knowing X^2 but not = knowing X? -----Original Message----- From: Alan.Shusterman.-at-.directory.Reed.EDU [mailto:Alan.Shusterman.-at-.directory.Reed.EDU] Sent: Wednesday, May 28, 2003 1:50 PM To: chemistry.-at-.ccl.net Subject: CCL:Orbitals Some of the postings on this subject have cited *correlations* between orbital properties and physical observables as evidence that orbitals = "in some sense" exist. example: If MOs have no physical reality for multielectron species, why = (a) is Koopmans' theorem useful, why (b) do photoelectron spectra match the predictions = of MO energy-level diagrams, and why (c) does the Hueckel 4n+2 rule, which is based on MO diagrams, work? (E. Lewars) example: Orbitals can also, in a sense, be observed experimentally. (M. Johansson) I'm sympathetic to these statements, but I prefer Jens' point of view. I am writing not to cast my vote, but to point out an interesting (to = me, anyway) parallel. I teach organic chemistry every fall semester, and = every year I must convince my students that *resonance contributors* do not = exist even though one can correlate physical observables with the properties = of these contributors. Some may still insist that, "if we routinely think of object X to make = a prediction, then object X exists, at least in our minds". This is an interesting idea, but I don't think that it relates well to "existence" = in the way chemists use this word. I'd like to thank everyone who has contributed to this discussion so = far. It has been interesting. -Alan =3D=3D=3D=3D Alan Shusterman Department of Chemistry Reed College Portland, OR academic.reed.edu/chemistry/alan/ -=3D This is automatically added to each message by mailing script =3D- To send e-mail to subscribers of CCL put the string CCL: on your = Subject: line and send your message to: CHEMISTRY.-at-.ccl.net Send your subscription/unsubscription requests to: = CHEMISTRY-REQUEST.-at-.ccl.net HOME Page: http://www.ccl.net | Jobs Page: http://www.ccl.net/jobs=20 If your mail is bouncing from CCL.NET domain send it to the maintainer: Jan Labanowski, jkl.-at-.ccl.net (read about it on CCL Home Page) -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+= ------_=_NextPart_001_01C32555.0155E480 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable CCL: RE: Orbitals

This may only show that my mind is *Really* = contaminated by the calculational methods, but I tend to think of the = orbitals as the mathematical building blocks out of which the wave = function is constructed, as a linear combination of the determinants = thereof.  A multi-electron wave function is just too complicated = to comprehend in its entirety. 

But (I think this is true) if you include the = contributions of all determinants made from the entire set of = orbitals--i.e. full CI with no approximations--the orbitals are not = unique and any set of orbitals that "spans the vector space," = as a mathematician would put it, can be used.

--David Shobe
S=FCd-Chemie Inc.
phone (502) 634-7409
fax     (502) 634-7724
email  dshobe.-at-.sud-chemieinc.com

Don't bother flaming me: I'm behind a = firewall.

P.S. I wonder if one could define the HOMO at least = by reversing Koopman's theorem and calculating the HOMO from the = electron density difference between the molecule and its = "vertical" radical cation.  And similarly with the LUMO = using the vertical radical anion, if it exists.  Or does one = necessarily run into Guosheng Wu's paradox of knowing X^2  but not = knowing X?



-----Original Message-----
From: Alan.Shusterman.-at-.directory.Reed.EDU
[mailto:Alan.Shusterma= n.-at-.directory.Reed.EDU]
Sent: Wednesday, May 28, 2003 1:50 PM
To: chemistry.-at-.ccl.net
Subject: CCL:Orbitals


Some of the postings on this subject have cited = *correlations* between orbital properties and physical observables as = evidence that orbitals "in some sense" exist.

example: If MOs have no physical reality for = multielectron species, why (a) is Koopmans'
theorem useful,  why (b) do photoelectron = spectra match the predictions of MO
energy-level diagrams, and why (c) does the Hueckel = 4n+2 rule, which is based on
MO diagrams, work? (E. Lewars)

example: Orbitals can also, in a sense, be observed = experimentally. (M. Johansson)

I'm sympathetic to these statements, but I prefer = Jens' point of view.

I am writing not to cast my vote, but to point out an = interesting (to me, anyway) parallel. I teach organic chemistry every = fall semester, and every year I must convince my students that = *resonance contributors* do not exist even though one can correlate = physical observables with the properties of these = contributors.

Some may still insist that, "if we routinely = think of object X to make a prediction, then object X exists, at least = in our minds". This is an interesting idea, but I don't think that = it relates well to "existence" in the way chemists use this = word.

I'd like to thank everyone who has contributed to = this discussion so far. It has been interesting.

-Alan

=3D=3D=3D=3D
Alan Shusterman
Department of Chemistry
Reed College
Portland, OR
academic.reed.edu/chemistry/alan/



-=3D This is automatically added to each message by = mailing script =3D-
To send e-mail to subscribers of CCL put the string = CCL: on your Subject: line
and send your message to:  = CHEMISTRY.-at-.ccl.net

Send your subscription/unsubscription requests to: = CHEMISTRY-REQUEST.-at-.ccl.net
HOME Page: http://www.ccl.net   | Jobs Page: http://www.ccl.net/jobs

If your mail is bouncing from CCL.NET domain send it = to the maintainer:
Jan Labanowski,  jkl.-at-.ccl.net (read about it on = CCL Home Page)
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-= +-+-+-+-+




------_=_NextPart_001_01C32555.0155E480-- ------=_NextPartTM-000-67f96a30-3d23-4b14-834c-ca372b14676f-- From chemistry-request@ccl.net Wed May 28 17:00:06 2003 Received: from smtp1.uh.cu (smtp1.uh.cu [200.55.139.212]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SKxtgC017664 for ; Wed, 28 May 2003 17:00:02 -0400 Received: from localhost (localhost.localdomain [127.0.0.1]) by smtp1.uh.cu (Postfix) with ESMTP id 837D734EE5 for ; Wed, 28 May 2003 17:00:42 -0400 (CDT) Received: from fq.uh.cu (canaria.qct.fq.oc.uh.cu [192.168.3.4]) by smtp1.uh.cu (Postfix) with ESMTP id 54512348AB for ; Wed, 28 May 2003 17:00:42 -0400 (CDT) Received: from localhost (rachel@localhost) by fq.uh.cu (8.9.0/8.8.7) with SMTP id QAA21861 for ; Wed, 28 May 2003 16:08:27 -0400 Date: Wed, 28 May 2003 16:08:27 -0400 (CDT) From: Rachel Crespo Otero Reply-To: Rachel Crespo Otero To: CHEMISTRY-.at.-ccl.net Subject: Zero point corrections Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Virus-Scanned: by AMaViS snapshot-20020300 Hello CCL members!! I have a question: When Zero-Point Vibration Energy Corrections are necessary? and why? Thanks Rachel From chemistry-request@ccl.net Wed May 28 16:51:23 2003 Received: from alvin.unc.edu.ar (alvin.unc.edu.ar [170.210.248.4]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SKpDgC017455 for ; Wed, 28 May 2003 16:51:17 -0400 Received: from dqb.fcq.unc.edu.ar (localhost.localdomain [127.0.0.1]) by alvin.unc.edu.ar (8.11.6/8.11.6) with ESMTP id h4SKoc111222 for ; Wed, 28 May 2003 17:50:40 -0300 Received: from fer-net.fcq.unc.edu.ar (localhost.localdomain [127.0.0.1]) by dqb.fcq.unc.edu.ar (8.9.3/8.9.3) with SMTP id SAA03389 for ; Wed, 28 May 2003 18:30:15 -0300 Content-Type: text/plain; charset="iso-8859-1" From: Marcos Villarreal To: chemistry.-at-.ccl.net Subject: phi/psi map Date: Wed, 28 May 2003 17:57:09 -0300 X-Mailer: KMail [version 1.2] MIME-Version: 1.0 Message-Id: <03052817570900.03559.-at-.fer-net.fcq.unc.edu.ar> Content-Transfer-Encoding: 8bit Hello, Is it posible to compute a phi/psi map for a carbohydrate within TINKER? Thanks in advance, Marcos Villarreal Grupo de Biofisica Departamento de Quimica Biologica - CIQUIBIC. Universidad Nacional de Cordoba. Cordoba. Argentina. http://www.fcq.unc.edu.ar/ciquibic From chemistry-request@ccl.net Wed May 28 17:04:08 2003 Received: from sungod.ccs.yorku.ca (sungod.ccs.yorku.ca [130.63.236.104]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SL48gC017750 for ; Wed, 28 May 2003 17:04:08 -0400 Received: from mountain.chem.yorku.ca (mountain.chem.yorku.ca [130.63.133.28]) by sungod.ccs.yorku.ca (8.12.9/8.12.8) with SMTP id h4SL48uG000019 for ; Wed, 28 May 2003 17:04:08 -0400 (EDT) Date: Wed, 28 May 2003 16:51:44 -0400 (EDT) From: Rene Fournier - 1999-07-07 X-Sender: renef.-at-.mountain.chem.yorku.ca To: chemistry.-at-.ccl.net Subject: orbitals Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Leif Laaksonen makes an important point: only observables are "real" in QM. So the question arises: is it possible to define orbitals as QM observables. It entirely depends on how you define the word "orbital". If one says orbitals are one-electron functions and nothing more, then of course orbitals can be made to be QM observables. For example, just integrate an exact squared wavefunction over all electron coordinates but one to get the electron density, then take the square root, multiply by a phase factor and you get "density orbitals". [G Hunter, Int J Quantum Chem 9 (1975) 237]. They may not be very useful as orbitals, but they are "real" in the sense of QM observables. Orbitals are always defined as one-electron functions, but THAT does not make them "unreal". The electron density is a one electron function and very real for any N-electron system, not only for the H atom. One "ab initio" way to define orbitals is to start from exact wavefunctions and calculate the overlap of a N-electron wavefunction (neutral) and the ground and various excited states a (N-1)-electron wavefunction (ion) (Dyson orbitals are defined in such a way I think). I'm sure there are definitions that will make such orbitals unique, but does that make them QM observables? I don't think so, but I'd like to hear from the CCL community on that. There are other ways to define orbitals > from exact wavefunctions, I'm sure: are any of them QM observables? As for Kohn-Sham orbitals, they may not be real individually but the N lowest energy ones squared and summed give the true electron density (an observable) and the negative of the KS HOMO energy is exactly equal to the first IP (another observable) so there are at least some bits of reality built in KS orbitals! Here's some relevant articles: 1) Kohn, Becke, Parr, J Phys Chem 100 (1996) 12974 2) "Kohn-Sham Orbitals and Orbital Energies: Fictitious Constructs but Good Approximations All the Same" by S. Hamel, P. Duffy, M.E. Casida, and D.R. Salahub Journal of Electron Spectroscopy and Related Phenomena (2002?) 3) Chong, Gritsenko, Baerends, J Chem Phys 116 (2002) 1760 -------------------------------------------------------------------- | Rene Fournier | Office: 303 Petrie | | Chemistry Dpt, York University| Phone: (416) 736 2100 Ext. 30687 | | 4700 Keele Street, Toronto | FAX: (416)-736-5936 | | Ontario, CANADA M3J 1P3 | e-mail: renef.-at-.yorku.ca | -------------------------------------------------------------------- | http://www.chem.yorku.ca/profs/renef/ | -------------------------------------------------------------------- From chemistry-request@ccl.net Wed May 28 17:17:30 2003 Received: from monty.richmond.edu (monty.richmond.edu [141.166.188.13]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SLHAgC018085 for ; Wed, 28 May 2003 17:17:30 -0400 Received: from penny.richmond.edu (penny.richmond.edu [141.166.188.34]) by monty.richmond.edu (8.11.6/8.11.6) with SMTP id h4SLH2H00523 for ; Wed, 28 May 2003 17:17:02 -0400 Received: from polyester.richmond.edu ([141.166.188.14]) by penny.richmond.edu (NAVGW 2.5.2.17) with SMTP id M2003052817170222633 for ; Wed, 28 May 2003 17:17:02 -0400 Received: from rocky.richmond.edu (rocky.richmond.edu [141.166.218.235]) by polyester.richmond.edu (8.11.6/8.11.6) with ESMTP id h4SLH2p14127 for ; Wed, 28 May 2003 17:17:02 -0400 Received: (from apache@localhost) by rocky.richmond.edu (8.11.6/8.11.6) id h4SLH0w01974; Wed, 28 May 2003 17:17:00 -0400 X-Authentication-Warning: rocky.richmond.edu: apache set sender to donnie.berkholz.-at-.richmond.edu using -f Received: from 216.88.164.254 (SquirrelMail authenticated user db6ug) by spidermail.richmond.edu with HTTP; Wed, 28 May 2003 16:17:00 -0500 (CDT) Message-ID: <12068.216.88.164.254.1054156620.squirrel.-at-.spidermail.richmond.edu> Date: Wed, 28 May 2003 16:17:00 -0500 (CDT) Subject: Re: CCL:Spam, CCL, and me... From: "donnie berkholz" To: In-Reply-To: <5.1.0.14.0.20030528133927.00b2e270.-at-.semovm.semo.edu> References: <5.1.0.14.0.20030528133927.00b2e270.-at-.semovm.semo.edu> X-Priority: 3 Importance: Normal X-Mailer: SquirrelMail (version 1.2.10) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-MailScanner: Found to be clean X-MailScanner-SpamCheck: not spam, SpamAssassin (score=-21.1, required 5, IN_REP_TO, QUOTED_EMAIL_TEXT, REFERENCES, REPLY_WITH_QUOTES, X_AUTH_WARNING) Various locations archive mailing lists and allow them to be read as newsgroups. Some mailing list software allows posting-only access, so one can read and post via nntp without receiving all the email in addition. Regular mailing-list users are totally unaffected by this and may ignore its existence, but those who wish to use newsgroup access may do so instead. See gmane.org for a good example of this. > This would not be helpful at all if one is at an > institution lacking decent newsgroup access. > E-mail is a much more generally available to > a wide variety of subscribers. > > AJD > > At 05:33 PM 5/28/2003 +0200, you wrote: >>Hello ! >> >>Would'n it be a good idea to convert the CCL Mailing list to a >> newsgroup ? >> >>Maybe this would have other disadvantages, but bringing much >> advantages, too: >> >>Sorted threads, moderation, reading by web interface, ... >> >>Bye >>Elmar >> > > Anthony J. Duben > Professor and Chairman > Computer Science Department > Mail Stop 5950 > Southeast Missouri State University > 1 University Plaza > Cape Girardeau MO 63701-4799 > phone: 573-651-2194 > fax: 573-651-2791\ > e-mail: ajduben.-at-.semo.edu > > "When life is very bad, two things make life > worth living: Mozart and quantum mechanics." > -- Victor Weisskopf > > > > -= This is automatically added to each message by mailing script =- To > send e-mail to subscribers of CCL put the string CCL: on your Subject: > line and send your message to: CHEMISTRY.-at-.ccl.net > > Send your subscription/unsubscription requests to: > CHEMISTRY-REQUEST.-at-.ccl.net HOME Page: http://www.ccl.net | Jobs Page: > http://www.ccl.net/jobs > > If your mail is bouncing from CCL.NET domain send it to the maintainer: > Jan Labanowski, jkl.-at-.ccl.net (read about it on CCL Home Page) > -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -- Donnie Berkholz News Editor, The Collegian University of Richmond 28 Westhampton Way University of Richmond, VA 23173 Cell: (612) 991-1321 AIM: spyderous From chemistry-request@ccl.net Wed May 28 18:50:08 2003 Received: from smtp805.mail.sc5.yahoo.com (smtp805.mail.sc5.yahoo.com [66.163.168.184]) by server.ccl.net (8.12.8/8.12.8) with SMTP id h4SMo8gC020765 for ; Wed, 28 May 2003 18:50:08 -0400 Received: from cat207.cqe.northwestern.edu (HELO chem.northwestern.edu) (a-beim=at=sbcglobal.net@129.105.122.207 with plain) by smtp-sbc-v1.mail.vip.sc5.yahoo.com with SMTP; 28 May 2003 22:50:07 -0000 Date: Wed, 28 May 2003 17:50:09 -0500 Subject: Re: CCL:UV spectrum calculation (new question) Content-Type: text/plain; charset=US-ASCII; format=flowed Mime-Version: 1.0 (Apple Message framework v552) Cc: chemistry=at=ccl.net To: sergiusz.kwasniewski=at=luc.ac.be From: Geoff Hutchison In-Reply-To: <1054105283.3ed45ec36b3f6=at=webmail.luc.ac.be> Message-Id: Content-Transfer-Encoding: 7bit X-Mailer: Apple Mail (2.552) > I'm curious how well INDO/S-RPA works against INDO/S-CIS for large > systems. > I only remember one article by M. Zerner quite a long time ago.. A comparison of ZINDO/RPA vs. ZINDO/CIS on various conjugated oligomers is included as part of my larger paper (which also compares HF/CIS, HF/RPA, TDDFT/CIS and TDDFT/RPA): J. Phys. Chem. A (2002) 106(44) p. 10596-10605. At the time, the only ZINDO/RPA I could put my hands on was contributed by Sergei Tretiak and Shaul Mukamel, which didn't let me set an active space. (In fact, it uses the Lanczos method for a full active space.) A parameterization for RPA calculations or a smaller active space would probably help. > Probably the calculation takes a lot longer (Hamiltonian matrix is > four times > as big since mixing of particle-hole and hole-particle excitations > occurs). I think with an efficient implementation, it's not really an issue. (It's a semiempirical calc. after all!) I never did timing tests, but I can relate that up to 60+ heavy atoms, ZINDO/RPA calculations still only took something on the order of minutes (on an 800MHz Pentium III, so faster times nowadays). > Are there any problems with numerical instabilities with the > implemented RPA scheme in a INDO/S-RPA calculation ? I'll second Dr. Thompson's comments. I haven't run any extremely "strange" molecules, but haven't seen any instabilities. Cheers, -Geoff -- -Geoff Hutchison Ratner/Marks Groups (847) 491-3295 Northwestern Chemistry http://www.chem.northwestern.edu/ From chemistry-request@ccl.net Wed May 28 20:19:00 2003 Received: from mail-01.med.umich.edu ([141.214.93.149]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4T0J0gC022116 for ; Wed, 28 May 2003 20:19:00 -0400 Received: from gwia-01-MTA by mail-01.med.umich.edu with Novell_GroupWise; Wed, 28 May 2003 20:18:59 -0400 Message-Id: X-Mailer: Novell GroupWise Internet Agent 6.0.2 Date: Wed, 28 May 2003 20:18:42 -0400 From: "Renxiao Wang" To: Subject: A question on heat of formation Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Content-Disposition: inline Hi, CCLers! Should the heat of formations of two enantiomers of a chiral compound be identical? I think the answer is yes. Please point out some references for this. A disturbing fact is that, no matter you use QM or MM to calculate the heat of formation for a given molecule, the number is conformation-depentdent. I guess this is because of the steric energy part is conformation-dependent. So, if I really want to compare the stability of two molecules using heat of formation, how may I calculate it right? Best regards, Renxiao Wang renxiao(at)med.umich.edu From chemistry-request@ccl.net Wed May 28 18:52:40 2003 Received: from suncom.rz.hu-berlin.de (suncom.rz.hu-berlin.de [141.20.1.31]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h4SMqdgC020851 for ; Wed, 28 May 2003 18:52:40 -0400 Received: from impact1.chemie.hu-berlin.de (impact1.chemie.hu-berlin.de [141.20.72.25]) by suncom.rz.hu-berlin.de (8.9.3/8.9.3) with ESMTP id AAA14578 for ; Thu, 29 May 2003 00:52:35 +0200 (MET DST) Received: (from ah@localhost) by impact1.chemie.hu-berlin.de (SGI-8.9.3/8.9.3) id AAA26152 for chemistry(at)ccl.net; Thu, 29 May 2003 00:52:34 +0200 (MESZ) Date: Thu, 29 May 2003 00:52:34 +0200 From: "Dr. Alexander Hofmann" To: ccl Subject: Re: CCL:Eigenvalues of hessian Message-ID: <20030529005234.A419506(at)chemie.hu-berlin.de> Reply-To: ah(at)chemie.hu-berlin.de References: <1054131647.16827.13.camel@charly> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from prsjjr(at)bath.ac.uk on Wed, May 28, 2003 at 04:37:04PM +0100 Hi Daniel, you normally get 3N eigenvalues. 3 are translations and 3 for rotation of the molecule. In solids, it becomes a little more difficult. Please check your modes for these movements. Hth Alex > -----Original Message----- > From: Computational Chemistry List [mailto:chemistry-request(at)ccl.net]On > Behalf Of Daniel R. Rohr > Sent: 28 May 2003 15:21 > To: ccl > Subject: CCL:Eigenvalues of hessian > > > Hi CCLers > > Does anybody of you know, why there are more than 3N-6 nonzero > eigenvalues of the hessian? I am especially interested in the question, > whether this error is due to the errors made by differentiation or > whether they are due to an error within the method itself. I usually get > only 3 zero eigenvalues. No matter if the hessian is calculated on a > stationary point or not. > > Thanks for your help > > Daniel Rohr > > -- > ----------------------------------------------------------------------- > Daniel Rohr Fachbereich Chemie der > Philipps-Universitdt > Tel.: +49-6421-28-25686 Hans-Meerwein-Stra_e > Fax.: +49-6421-28-25566 D-35043 Marburg > eMail: rohrd(at)stud-mailer.uni-marburg.de Germany > ----------------------------------------------------------------------- > > > > > > > > > > > > > > > > -= This is automatically added to each message by mailing script =- > To send e-mail to subscribers of CCL put the string CCL: on your Subject: line > and send your message to: CHEMISTRY(at)ccl.net > > Send your subscription/unsubscription requests to: CHEMISTRY-REQUEST(at)ccl.net > HOME Page: http://www.ccl.net | Jobs Page: http://www.ccl.net/jobs > > If your mail is bouncing from CCL.NET domain send it to the maintainer: > Jan Labanowski, jkl(at)ccl.net (read about it on CCL Home Page) > -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > > > > -- Dr. Alexander Hofmann Humboldt-Universitaet zu Berlin Institut fuer Chemie Arbeitsgruppe Quantenchemie Post: Unter den Linden 6 10099 Berlin Visitors: Brook-Taylor-Strasse 2 12489 Berlin ah(at)chemie.hu-berlin.de Tel.: +49-30-2093-7138 Fax.: +49-30-2093-7136 http://www.chemie.hu-berlin.de/ag_sauer/index.html PGP-Key: wwwkeys.de.pgp.net ID: D9D62D35 From chemistry-request@ccl.net Wed May 28 18:45:44 2003 Received: from web10406.mail.yahoo.com (web10406.mail.yahoo.com [216.136.130.98]) by server.ccl.net (8.12.8/8.12.8) with SMTP id h4SMjigC020595 for ; Wed, 28 May 2003 18:45:44 -0400 Message-ID: <20030528224544.55154.qmail(at)web10406.mail.yahoo.com> Received: from [40.0.40.10] by web10406.mail.yahoo.com via HTTP; Wed, 28 May 2003 15:45:44 PDT Date: Wed, 28 May 2003 15:45:44 -0700 (PDT) From: Guosheng Wu Subject: Re: CCL:orbitals To: chemistry(at)ccl.net MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii --- Rene Fournier - 1999-07-07 wrote: > Leif Laaksonen makes an important point: only observables > are "real" in QM. So the question arises: is it possible to > define orbitals as QM observables. It entirely depends on > how you define the word "orbital". If one says orbitals are > one-electron functions and nothing more, then of course orbitals > can be made to be QM observables. For example, just integrate > an exact squared wavefunction over all electron coordinates > but one to get the electron density, then take the square > root, multiply by a phase factor and you get "density orbitals". > [G Hunter, Int J Quantum Chem 9 (1975) 237]. They may not be > very useful as orbitals, but they are "real" in the sense of > QM observables. It's not clear for me how you define "QM observable"? MO is certainly not "observable", if "observable" is defined as something can be measured directly or indirectly by an experiment. For example, electronic density, ionization energy, and so on. The issue is related with the phase factor you mentioned: From experimental data, one can get |MO|^2 at a certain position, but here "MO" is not unique: MO = |MO|*[cos(theta)+i*sin(theta)], where "theta" can be any arbitary value. This may be traced back to the Uncertainty Principles. Similarly to my original post, 0, 1, 2,... are countable (defined as non-negative integers). However, if one do the square of 1, +1 and -1 will come out, not unique --- 2 directions in the 1-D space; Do the square of -1, we get +i and -i, 2 direction in the 2-D space... It seems we can safely say that -1 & i are not countable!? By the way, does it really matter if "MO" is observable or not in any sense? Maybe useful for teaching. Guosheng > --- Rene Fournier - 1999-07-07 wrote: > > Leif Laaksonen makes an important point: only observables > > are "real" in QM. So the question arises: is it possible to > > define orbitals as QM observables. It entirely depends on > > how you define the word "orbital". If one says orbitals are > > one-electron functions and nothing more, then of course orbitals > > can be made to be QM observables. For example, just integrate > > an exact squared wavefunction over all electron coordinates > > but one to get the electron density, then take the square > > root, multiply by a phase factor and you get "density orbitals". > > [G Hunter, Int J Quantum Chem 9 (1975) 237]. They may not be > > very useful as orbitals, but they are "real" in the sense of > > QM observables. > > Orbitals are always defined as one-electron functions, > > but THAT does not make them "unreal". The electron density > > is a one electron function and very real for any N-electron > > system, not only for the H atom. > > One "ab initio" way to define orbitals is to start from > > exact wavefunctions and calculate the overlap of a N-electron > > wavefunction (neutral) and the ground and various excited > > states a (N-1)-electron wavefunction (ion) (Dyson orbitals are > > defined in such a way I think). I'm sure there are definitions > > that will make such orbitals unique, but does that make them > > QM observables? I don't think so, but I'd like to hear from > > the CCL community on that. There are other ways to define orbitals > > > from exact wavefunctions, I'm sure: are any of them QM observables? > > As for Kohn-Sham orbitals, they may not be real individually > > but the N lowest energy ones squared and summed give the true > > electron density (an observable) and the negative of the KS HOMO > > energy is exactly equal to the first IP (another observable) so > > there are at least some bits of reality built in KS orbitals! > > > > Here's some relevant articles: > > > > 1) Kohn, Becke, Parr, J Phys Chem 100 (1996) 12974 > > 2) "Kohn-Sham Orbitals and Orbital Energies: Fictitious Constructs but > > Good Approximations All the Same" > > by S. Hamel, P. Duffy, M.E. Casida, and D.R. Salahub > > Journal of Electron Spectroscopy and Related Phenomena (2002?) > > 3) Chong, Gritsenko, Baerends, J Chem Phys 116 (2002) 1760 > > > > -------------------------------------------------------------------- > > | Rene Fournier | Office: 303 Petrie | > > | Chemistry Dpt, York University| Phone: (416) 736 2100 Ext. 30687 | > > | 4700 Keele Street, Toronto | FAX: (416)-736-5936 | > > | Ontario, CANADA M3J 1P3 | e-mail: renef(at)yorku.ca | > > -------------------------------------------------------------------- > > | http://www.chem.yorku.ca/profs/renef/ | > > -------------------------------------------------------------------- > > > > > > > > -= This is automatically added to each message by mailing script =- > > To send e-mail to subscribers of CCL put the string CCL: on your Subject: line > > and send your message to: CHEMISTRY(at)ccl.net > > > > Send your subscription/unsubscription requests to: CHEMISTRY-REQUEST(at)ccl.net > > HOME Page: http://www.ccl.net | Jobs Page: http://www.ccl.net/jobs > > > > If your mail is bouncing from CCL.NET domain send it to the maintainer: > > Jan Labanowski, jkl(at)ccl.net (read about it on CCL Home Page) > > -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > > > > > > > > > > > > __________________________________ > Do you Yahoo!? > Yahoo! Calendar - Free online calendar with sync to Outlook(TM). > http://calendar.yahoo.com > __________________________________ Do you Yahoo!? Yahoo! Calendar - Free online calendar with sync to Outlook(TM). http://calendar.yahoo.com