From chemistry-request@server.ccl.net Fri Aug 11 03:53:38 2000 Received: from linus.imcm.cas.cz (Linus.imcm.cas.cz [147.231.77.250]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id DAA01804 for ; Fri, 11 Aug 2000 03:53:37 -0400 Received: from thales (thales.imcm.cas.cz [147.231.77.130]) by linus.imcm.cas.cz (8.9.3/8.9.3) with ESMTP id JAA06297 for ; Fri, 11 Aug 2000 09:48:46 +0200 Message-Id: <200008110748.JAA06297@linus.imcm.cas.cz> From: "Petr Toman" To: chemistry@ccl.net Date: Fri, 11 Aug 2000 09:49:57 +0200 MIME-Version: 1.0 Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7BIT Subject: Atomic charges: Ni, Co Reply-to: toman@imc.cas.cz Priority: normal X-mailer: Pegasus Mail for Win32 (v3.12a) Dear CCLers, I wonder if there is a suitable method for calculation of atomic charges in molecules containing Ni or Co. I tried Pop=MK in Gaussian 98, but... Merz-Kollman atomic radii used. GetVDW: no radius for atom 1 atomic number 28. Of course, it is possible to use Mulliken population analysis, but I am not sure if it is the best way. Thanks a lot. Best regards, Petr Toman From chemistry-request@server.ccl.net Fri Aug 11 05:58:37 2000 Received: from hydra.chem.rug.nl (hydra.chem.rug.nl [129.125.35.229]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id FAA02502 for ; Fri, 11 Aug 2000 05:58:36 -0400 Received: from [129.125.7.13] (theochem1.chem.rug.nl [129.125.7.13]) by hydra.chem.rug.nl (AIX4.2/UCB 8.7/8.7) with ESMTP id LAA34658; Fri, 11 Aug 2000 11:53:45 +0200 (MET DST) Mime-Version: 1.0 X-Sender: swart@hydra.chem.rug.nl Message-Id: In-Reply-To: <200008110748.JAA06297@linus.imcm.cas.cz> References: <200008110748.JAA06297@linus.imcm.cas.cz> Date: Fri, 11 Aug 2000 11:56:49 +0200 To: "Petr Toman" From: Marcel Swart Subject: Re: CCL:Atomic charges: Ni, Co Cc: CHEMISTRY@ccl.net Content-Type: text/plain; charset="us-ascii" ; format="flowed" >Dear CCLers, >I wonder if there is a suitable method for calculation of atomic charges >in molecules containing Ni or Co. >I tried Pop=MK in Gaussian 98, but... > Merz-Kollman atomic radii used. > GetVDW: no radius for atom 1 atomic number 28. > >Of course, it is possible to use Mulliken population analysis, but I am >not sure if it is the best way. > >Thanks a lot. > >Best regards, >Petr Toman Sure there is. We have recently developed a Multipole Derived Charge analysis, which gives the most acurrate charge description possible in DFT. (The paper has been accepted to appear in J.Comput.Chem.) Since there are NO parameters like for instance the MK-radii, as long as the calculation on the molecule is possible, the charges can be obtained, and are the best description of the charge distribution within that (DFT)-calculation. It has been implemented in the ADF program. Marcel Swart. From chemistry-request@server.ccl.net Fri Aug 11 09:05:15 2000 Received: from theory.tc.cornell.edu (tc.cornell.edu [128.84.30.174]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id JAA04165 for ; Fri, 11 Aug 2000 09:05:15 -0400 Received: from tc.cornell.edu (norbert.tc.cornell.edu [128.84.20.68]) by theory.tc.cornell.edu (8.8.4/8.8.3/CTC-1.0) with ESMTP id JAA17920 for ; Fri, 11 Aug 2000 09:00:18 -0400 Message-ID: <3993F844.639BE41B@tc.cornell.edu> Date: Fri, 11 Aug 2000 08:57:40 -0400 From: Richard Gillilan X-Mailer: Mozilla 4.7 [en] (WinNT; I) X-Accept-Language: en MIME-Version: 1.0 CC: chemistry@ccl.net Subject: Re: CCL:single linkage cluster analysis References: <3992C57A.95E0C1D0@chemistry.upatras.gr> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Both of these books by Helmuth Spath contain extensive FORTRAN listings for clustering. "Cluster Dissection and Analysis Theory, FORTRAN programs and examples" Helmuth Spath, John Wiley & Sons 1985 ISBN 0-85312-736-0 QA 278 S73 C74 Also "Cluster Analysis Algorithms for data reduction and classification of objects" Helmuth Spath, John Wiley & Sons 1980 QA 278 S73 1980 ISBN 0-85312-141-9 Richard Gillilan Cornell Theory Center From chemistry-request@server.ccl.net Fri Aug 11 01:07:41 2000 Received: from lrz.uni-muenchen.de (lsanca1-ar99-078-106.biz.dsl.gtei.net [4.3.78.106]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id BAA01262 for ; Fri, 11 Aug 2000 01:07:40 -0400 Received: (from eugene.leitl@localhost) by lrz.uni-muenchen.de (8.8.8/8.8.8) id VAA30340; Thu, 10 Aug 2000 21:00:53 -0700 From: Eugene Leitl MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <14739.31348.312976.172247@lrz.uni-muenchen.de> Date: Thu, 10 Aug 2000 21:00:52 -0700 (PDT) To: , , Subject: fluorocarbonophilic? X-Mailer: VM 6.71 under 21.1 (patch 4) "Arches" XEmacs Lucid While working with florocarbon surfactant-stabilized perflorocarbon emulsions I noticed a perculiar affinity of perfluorinated compounds to themselves, and nothing else. In a sense, one could see them to define another axis in addition to hydrophobic-hydrophilic. What is the origin of this specific interaction? Dipole-dipole, entropic (residue packing)? Does the phenomenon also appear in molecular dynamics simulations of, say, ternary (water, lipid, perfluorocarbon) systems? Intrigued, -- Eugene Leitl From chemistry-request@server.ccl.net Fri Aug 11 06:46:24 2000 Received: from wn1.sci.kun.nl (wn1.sci.kun.nl [131.174.8.1]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id GAA02748 for ; Fri, 11 Aug 2000 06:46:23 -0400 Received: from sci.kun.nl by wn1.sci.kun.nl via vstofchem17.sci.kun.nl [131.174.190.185] with ESMTP id MAA08592 (8.8.8/3.29); Fri, 11 Aug 2000 12:41:33 +0200 (MET DST) Sender: jaccos@sci.kun.nl Message-ID: <3993D85D.35686035@sci.kun.nl> Date: Fri, 11 Aug 2000 12:41:33 +0200 From: Jacco van de Streek Organization: Dept. of Solid State Chem. X-Mailer: Mozilla 4.07C-SGI [en] (X11; I; IRIX 6.5 IP22) MIME-Version: 1.0 To: chemistry@ccl.net, Petr Toman Subject: Re: CCL:Atomic charges: Ni, Co References: <200008110748.JAA06297@linus.imcm.cas.cz> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Petr Toman wrote: > > Dear CCLers, > I wonder if there is a suitable method for calculation of atomic charges > in molecules containing Ni or Co. > I tried Pop=MK in Gaussian 98, but... > Merz-Kollman atomic radii used. > GetVDW: no radius for atom 1 atomic number 28. This seems to be related to a recent question about the same topic. >From my own experience, best results for partial charges are obtained by: a. Using the set sampling points of Breneman & Wiberg (the 'ChelpG' keyword). b. Restricting the dipole moment (the 'Dipole' keyword). The command line then reads something like: # HF/6-31G** Pop=(ChelpG,Dipole) etc. The reference to the Breneman & Wiberg paper is: Breneman, C.M. & K.B. Wiberg (1990). J. Comp. Chem. 11, 361-373. ChelpG is the only method which uses a lot of sampling points, and it can cope with additional charge centres (MK can't in my experience, Gaussian crashes). Restricting the dipole moment has two advantages: a. At long distances, the monopole of a neutral molecule is neglegible (=zero), and the dipole interactions are next in importance. b. There are quite a lot of degrees of freedom, which can render some pairs of atoms ill-defined (dependent on each other). Restricting the dipole moment might not solve this problem completely, but at least will push the calculation in the right direction. If anyone can think of a disadvantage, I'd like to know. If the molecule contains atoms for which Gaussian has no atomic radius available, you must split your job (otherwise Gaussian crashes): 1. Run the optimisation / single point job, specifying a checkpoint file. 2. Run the ESP job. The command line for the second step reads: # HF/6-31G** Pop=(ChelpG,Dipole,ReadRadii) Density=CHK Geom=checkpoint etc. This indicates that both the electron density and the molecular geometry must be read from the checkpoint file. The 'ReadRadii' keyword indicates that at the end of the input radii for the ChelpG calculation are provided. The format of the radii is: Blank line 'Atomic number' 'radius in Angstrom' Blank line Blank line So for the calculation of the a molecule containing bromine, after having run the single point calculation, the entire input file is as simple as: ***************************************** $ RunGauss %Chk=C14H28Br2.chk # HF/6-31G** Pop=(ChelpG,Dipole,ReadRadii) Density=CHK SCF=Direct Geom=(checkpoint,NoDistance,NoAngle) 1,14-dibromotetradecane 0 1 35 1.85 ***************************************** I hope it is clear that your optimisation / single point job must contain '%Chk=C14H28Br2.chk' as its second line. Comments and experiences welcomed. Hope this helps, -- Jacco van de Streek (mailto:jaccos@sci.kun.nl) Dept. of Solid State Chemistry University of Nijmegen The Netherlands From chemistry-request@server.ccl.net Fri Aug 11 15:17:08 2000 Received: from ucidoor.unitedcatalysts.com ([208.23.162.2]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id PAA01620 for ; Fri, 11 Aug 2000 15:17:08 -0400 Received: by ucidoor.unitedcatalysts.com; (8.8.8/1.3/10May95) id PAA28715; Fri, 11 Aug 2000 15:17:05 -0400 (EDT) Received: from 10.1.0.50 by ucismtp02.unitedcatalysts.com (InterScan E-Mail VirusWall NT); Fri, 11 Aug 2000 15:16:43 -0400 (Eastern Daylight Time) Received: from lvlxch01.unitedcatalysts.com ([10.1.0.88]) by lvlmail.unitedcatalysts.com (PMDF V5.2-32 #33820) with ESMTP id <0FZ500B5772T39@lvlmail.unitedcatalysts.com>; Fri, 11 Aug 2000 15:20:54 -0400 (EDT) Received: by lvlxch01.unitedcatalysts.com with Internet Mail Service (5.5.2650.21) id <3YY6MM0C>; Fri, 11 Aug 2000 15:15:23 -0400 Content-return: allowed Date: Fri, 11 Aug 2000 15:15:13 -0400 From: "Shobe, Dave" Subject: RE: fluorocarbonophilic? To: "'Eugene Leitl'" , chemistry@ccl.net, orgchem@gwup.org, orglist@dq.fct.unl.pt Message-id: <157A51F55AAAD3119CD70008C7B1629D6384A4@lvlxch01.unitedcatalysts.com> MIME-version: 1.0 X-Mailer: Internet Mail Service (5.5.2650.21) 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 PAA01621 There was a recent Accounts of Chemical Research article on "fluorous" phases István T. Horváth ; Fluorous Biphase Chemistry, Accounts of Chemical Research; 1998; 31(10); 641-650. Maybe it has some useful references. Let me know what you find (and of the 3 lists you posted to I only read chemistry@ccl.net). Also: fluorous phases seem to have an affinity for O2. Maybe someone can explain that. --David Shobe Süd-Chemie Inc. phone (502) 634-7409 fax (502) 634-7724 email dshobe@sud-chemieinc.com Any opinions herein are not necessarily representative of Süd-Chemie. -----Original Message----- From: Eugene Leitl [mailto:eugene.leitl@lrz.uni-muenchen.de] Sent: Friday, August 11, 2000 12:01 AM To: chemistry@ccl.net; orgchem@gwup.org; orglist@dq.fct.unl.pt Subject: CCL:fluorocarbonophilic? While working with florocarbon surfactant-stabilized perflorocarbon emulsions I noticed a perculiar affinity of perfluorinated compounds to themselves, and nothing else. In a sense, one could see them to define another axis in addition to hydrophobic-hydrophilic. What is the origin of this specific interaction? Dipole-dipole, entropic (residue packing)? Does the phenomenon also appear in molecular dynamics simulations of, say, ternary (water, lipid, perfluorocarbon) systems? Intrigued, -- Eugene Leitl -= This is automatically added to each message by mailing script =- CHEMISTRY@ccl.net -- To Everybody | CHEMISTRY-REQUEST@ccl.net -- To Admins MAILSERV@ccl.net -- HELP CHEMISTRY or HELP SEARCH CHEMISTRY-SEARCH@ccl.net -- archive search | Gopher: gopher.ccl.net 70 Ftp: ftp.ccl.net | WWW: http://www.ccl.net/chemistry/ | Jan: jkl@ccl.net From chemistry-request@server.ccl.net Fri Aug 11 15:13:54 2000 Received: from ned1.sims.nrc.ca (ned1.sims.nrc.ca [132.246.108.2]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id PAA01563 for ; Fri, 11 Aug 2000 15:13:53 -0400 Received: from fm6 (fm6.sims.nrc.ca [132.246.100.170]) by ned1.sims.nrc.ca (8.8.8/8.8.8) with SMTP id PAA29544 for ; Fri, 11 Aug 2000 15:13:54 -0400 (EDT) Message-ID: <004301c003c8$48c6bb20$aa64f684@sims.nrc.ca> From: "Hongbin Du" To: Subject: Bond orders Date: Fri, 11 Aug 2000 15:13:51 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 X-Mimeole: Produced By Microsoft MimeOLE V5.50.4133.2400 Dear CCLers, Using Gaussian, NBO, AIMPAC etc., one can obtain several kinds of bond orders: AIM bond order, Wiberg Bond order, overlap-weighted NAO bond order, NLMO/NPA bond order (bo). Here are the questions: (1) Which is 'the best' to describe the bonding in molecules? In our recent study, only AIM bond order had the 'right' number (i.e. b.o. ~ 1.4 by comparison of the electron densities at the bond critical points with the standard compounds, Classical Lewis acid-base theory yields a bo of 1.5, while NBO analyses gave various bo around 1.0). Could somebody recommend any reference for their comparison? (2) What is the physical meaning for the negative NBO bond orders in the ? For example: Atom-Atom Net Linear NLMO/NPA Bond Orders: Atom 1 2 3 ... ---- ------ ------ ------ ... 1. C 0.0000 0.8174 0.7960 ... 2. N 0.8174 0.0000 -0.0104 ... 3. H 0.7960 -0.0104 0.0000 ... ... Thank you, Hongbin From chemistry-request@server.ccl.net Fri Aug 11 16:38:50 2000 Received: from wirehead.arqule.com (email.arqule.com [12.27.160.89]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id QAA01889 for ; Fri, 11 Aug 2000 16:38:49 -0400 Received: by WIREHEAD with Internet Mail Service (5.5.2650.21) id ; Fri, 11 Aug 2000 16:38:46 -0400 Message-ID: <6B00FB949906D211A88800104B8AE52001A55B28@WIREHEAD> From: "Manchester, John" To: "'chemistry@ccl.net'" Subject: QSARs for molar absorptivity? Date: Fri, 11 Aug 2000 16:38:46 -0400 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2650.21) Content-Type: text/plain; charset="iso-8859-1" Hi CCLers, I'm looking for methods to estimate extinction coefficients (seems like there ought to be some fragment-based models), or at least cheap ways to calculate the UV absorption spectra for lots of compounds. I'd be most grateful for any information, and will summarize for the net. Thanks in advance, John John Manchester Senior Scientist Computational Design & Informatics tel: 781-994-0317 ArQule, Inc. fax: 781-938-9789 19 Presidential Way jmanchester@arqule.com Woburn, MA 01801 http://www.arqule.com From chemistry-request@server.ccl.net Fri Aug 11 13:55:08 2000 Received: from umc-mail01.missouri.edu (umc-mail01.missouri.edu [128.206.10.216]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id NAA01116 for ; Fri, 11 Aug 2000 13:55:08 -0400 Received: from [128.206.98.1] (mu-098001.dhcp.missouri.edu [128.206.98.1]) by umc-mail01.missouri.edu with SMTP (Microsoft Exchange Internet Mail Service Version 5.5.2650.21) id QMW260LT; Fri, 11 Aug 2000 12:50:21 -0500 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Sender: HarrisR@pop.email.missouri.edu Message-Id: In-Reply-To: <14739.31348.312976.172247@lrz.uni-muenchen.de> Date: Fri, 11 Aug 2000 12:52:59 -0500 To: , , , Eugene Leitl From: "Robert E. Harris" Subject: Re: CCL:fluorocarbonophilic? >While working with florocarbon surfactant-stabilized perflorocarbon >emulsions I noticed a perculiar affinity of perfluorinated compounds >to themselves, and nothing else. In a sense, one could see them to >define another axis in addition to hydrophobic-hydrophilic. > >What is the origin of this specific interaction? Dipole-dipole, >entropic (residue packing)? Does the phenomenon also appear in >molecular dynamics simulations of, say, ternary (water, lipid, >perfluorocarbon) systems? > >Intrigued, > >-- Eugene Leitl > Some entropy, mostly interaction energy (dispersion interaction, mostly.) This sort of segregation is explained in solubility parameter theory mostly by interaction energy density. See, for example, "Solubility of Nonelectrolytes" 4th edition, by Hildebrand and Scott. Carbon tetrachloride-perfluoromethyl cyclohexane has an uppper critical solution tel]mperature of about 26 degrees C. That means these two are not mutually soluble in all proportions below that temperature. REH Robert E. Harris Phone: 573-882-3274. Fax: 573-882-2754 Department of Chemistry, University of Missouri-Columbia Columbia, Missouri, USA 65211 From chemistry-request@server.ccl.net Fri Aug 11 17:56:05 2000 Received: from night.its.uiowa.edu (night.its.uiowa.edu [128.255.56.106]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id RAA02467 for ; Fri, 11 Aug 2000 17:56:05 -0400 Received: from [128.255.72.43] (his.chem.uiowa.edu [128.255.72.43]) by night.its.uiowa.edu (8.9.3/8.9.1/ns-mx-1.9) with ESMTP id QAA44326 for ; Fri, 11 Aug 2000 16:56:04 -0500 Message-Id: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Fri, 11 Aug 2000 16:56:02 -0500 To: CHEMISTRY@ccl.net From: "Jan H. Jensen" Subject: Vibrational analysis w/ constraints Hi, I am interested in doing a vibrational analysis of a Hessian matrix calculated for a system that was optimized with geometric constraints. Can anyone point me to literature of this subject? Thanks, Jan Jensen =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Jan H. Jensen Assistant Professor Department of Chemistry jan-jensen@uiowa.edu University of Iowa Phone:(319) 335-1108 Iowa City, IA 52242 FAX: (319) 335-1270 http://www.uiowa.edu/~chemdept/faculty/jensen/ =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- From chemistry-request@server.ccl.net Fri Aug 11 19:00:19 2000 Received: from Mercury.acs.unt.edu (mercury.acs.unt.edu [129.120.220.1]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id TAA02783 for ; Fri, 11 Aug 2000 19:00:19 -0400 Received: from jove.acs.unt.edu (10759@jove.acs.unt.edu [129.120.220.41]) by Mercury.acs.unt.edu (8.8.8/8.8.8) with ESMTP id SAA05332 for ; Fri, 11 Aug 2000 18:00:12 -0500 (CDT) Received: from localhost (tdp0006@localhost) by jove.acs.unt.edu (8.8.8/8.8.8) with ESMTP id SAA07567 for ; Fri, 11 Aug 2000 18:00:12 -0500 (CDT) Date: Fri, 11 Aug 2000 18:00:12 -0500 (CDT) From: TREVOR D POWER To: CHEMISTRY@ccl.net Subject: Re: CCL:Vibrational analysis w/ constraints In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Jan, If you mean you want to perform a second-derivative vibrational frequency analysis on a geometry obtained from a partial geometry optimization, I have a couple of responses. To my knowledge there is no way to do such a thing with Gaussian. But, more importantly, why would you want to do such a thing? A vibrational analysis at some point, other than an extrema, is totally meaningless. The stationary point obtained >from a partial geometry optimization is not a true stationary point at all. Cheers, David Power Department of Chemistry University of North Texas NT Station, Box 305070 Denton, TX 76203-5070 tdp0006@unt.edu On Fri, 11 Aug 2000, Jan H. Jensen wrote: > Hi, > I am interested in doing a vibrational analysis of a Hessian matrix > calculated for a system that was optimized with geometric constraints. Can > anyone point me to literature of this subject? > > Thanks, Jan Jensen > > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- > Jan H. Jensen Assistant Professor > Department of Chemistry jan-jensen@uiowa.edu > University of Iowa Phone:(319) 335-1108 > Iowa City, IA 52242 FAX: (319) 335-1270 > http://www.uiowa.edu/~chemdept/faculty/jensen/ > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- > > > > -= This is automatically added to each message by mailing script =- > CHEMISTRY@ccl.net -- To Everybody | CHEMISTRY-REQUEST@ccl.net -- To Admins > MAILSERV@ccl.net -- HELP CHEMISTRY or HELP SEARCH > CHEMISTRY-SEARCH@ccl.net -- archive search | Gopher: gopher.ccl.net 70 > Ftp: ftp.ccl.net | WWW: http://www.ccl.net/chemistry/ | Jan: jkl@ccl.net > > > > > > From chemistry-request@server.ccl.net Fri Aug 11 22:14:31 2000 Received: from herald.cc.purdue.edu (herald.cc.purdue.edu [128.210.11.29]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id WAA03463 for ; Fri, 11 Aug 2000 22:14:31 -0400 Received: from [209.178.158.253] by herald.cc.purdue.edu with ESMTP for chemistry@ccl.net; Fri, 11 Aug 2000 21:14:26 -0500 Mime-Version: 1.0 Message-Id: Date: Fri, 11 Aug 2000 19:19:45 -0800 To: chemistry@ccl.net From: Eric Scerri Subject: orbital observation/latest suggestion Content-Type: text/plain; charset="us-ascii" ; format="flowed" Dear List members , A few days ago I posted an article I have written on the impossibility of observing orbitals which is due to appear in Journal of Chemical Education. I also posted this on another list and received the following response. I would like to ask the computational community whether they think there may be anything to this. It will require calculating the contribution to the ground state of copper (I) oxide made by the configuration given below. My own hunch is that this will not work but I have to confess that this seems plausible. Of course even if this argument is correct it still does not represent the observation of a single orbital such as dz2 in Cu(I) oxide as claimed in the Nature article, editorial and other popular science magazines. What it would presumably represent is the observation of the electron density due to all the combined densities due to all the Cu orbitals in Cu(I)oxide. So what I am requesting is for someone to do a C.I. calculation to see the extent to which the 4s1 3d9 configuration contributes. I would also be interested in general comments on this suggestion. Here is the suggestion from a colleague. ------------------------------------------------------------------------ Only two electron configurations make substantial contributions to the ground state in copper (I) oxide. The major contributor is the one we teach our freshmen for copper (I): 1s2 2s2 2p6 3s2 3p6 3d10. Since this is closed-shell, the "combined effects of many separate electron densities" is spherical about the copper nucleus. Then there is a small amount of configuration interaction with 3d9 4s1. This will have the shape of the singly-occupied d orbital. To have the right symmetry to mix with the closed-shell configuration, this must be dz2. ------------------------------ regards, ------------------------------------------------- Eric Scerri PhD, Editor of "Foundations of Chemistry" http://www.wkap.nl/journalhome.htm/1386-4238 From chemistry-request@server.ccl.net Fri Aug 11 22:17:46 2000 Received: from orion.chem.vt.edu (root@orion.chem.vt.edu [128.173.180.103]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id WAA03529 for ; Fri, 11 Aug 2000 22:17:46 -0400 Received: from localhost (crawdad@localhost) by orion.chem.vt.edu (8.9.3/8.9.3) with ESMTP id WAA02830; Fri, 11 Aug 2000 22:17:38 -0400 X-Authentication-Warning: orion.chem.vt.edu: crawdad owned process doing -bs Date: Fri, 11 Aug 2000 22:17:38 -0400 (EDT) From: "T. Daniel Crawford" X-Sender: crawdad@orion.chem.vt.edu To: TREVOR D POWER cc: CHEMISTRY@ccl.net Subject: Re: CCL:Vibrational analysis w/ constraints In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII A superb reference for computing force constants at constrained geometries is: "On the ab initio determination of higher-order force-constants at non-stationary reference geometries," W.D. Allen and A.G. Csaszar, J. Chem. Phys. /98/, 2983-3015 (1993). When the forces are not zero, one must project out rotational components of the quadratic force constants and take care in selecting internal coordinates. There are definitely good reasons to do such an analysis; Allen and Csaszar found that one can often obtain CCSD(T)-quality results simply by using high-accuracy experimental geometries as references with SCF frequencies, for example. -Daniel -- T. Daniel Crawford Department of Chemistry crawdad@vt.edu Virginia Polytechnic Institute and www.chem.vt.edu/chem-dept/crawford State University