From chemistry-request@server.ccl.net Tue Aug 1 03:08:40 2000 Received: from host23.lctn.u-nancy.fr (host23.lctn.u-nancy.fr [192.54.210.30]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id DAA22409 for ; Tue, 1 Aug 2000 03:08:39 -0400 From: assfeld@host23.lctn.u-nancy.fr Received: (from assfeld@localhost) by host23.lctn.u-nancy.fr (AIX4.3/8.9.3/8.9.3) id IAA18676 for chemistry@ccl.net; Tue, 1 Aug 2000 08:57:35 +0200 Date: Tue, 1 Aug 2000 08:57:35 +0200 Message-Id: <200008010657.IAA18676@host23.lctn.u-nancy.fr> To: chemistry@ccl.net Subject: Crystallography Database Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Content-MD5: /YgW4a8BLqsSsa7gW7c3Bw== Dear CCLers, I am looking for a (as cheap as possible!) database which contains fractional coordinates of various solids. That is because I found a paper in Acta Cryst., where the authors give only some distances, angles, space group, cell parameters,...but no fractional coordinates. I really don't know how to built a crystal without frac. coor. Yours. ...Xav Ast. Pr. Xavier Assfeld Xavier.Assfeld@lctn.u-nancy.fr Laboratoire de Chimie theorique (T) 33 3 83 91 21 49 Universite Henri Poincare (F) 33 3 83 91 25 30 F-54506 Nancy BP 239 http://www.lctn.u-nancy.fr From chemistry-request@server.ccl.net Tue Aug 1 05:41:18 2000 Received: from mail-c.bcc.ac.uk (mail-c.bcc.ac.uk [144.82.100.23]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id FAA23200 for ; Tue, 1 Aug 2000 05:41:18 -0400 Received: from ri.ac.uk (actually host davy.ri.ac.uk) by mail-c.bcc.ac.uk with SMTP (Mailer); Tue, 1 Aug 2000 10:40:23 +0100 Received: from landlord (nb-davidc) by ri.ac.uk (5.x/SMI-SVR4) id AA13892; Tue, 1 Aug 2000 10:39:28 +0100 Message-Id: <003001bffb9d$5b9e4700$c6503fc1@ri.ac.uk> From: David S Coombes To: assfeld , chemistry References: <200008010657.IAA18676@host23.lctn.u-nancy.fr> Subject: Re: CCL:Crystallography Database Date: Tue, 1 Aug 2000 10:46:24 +0100 Organization: Royal Institution of Great Britain 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 5.00.2919.6600 X-Mimeole: Produced By Microsoft MimeOLE V5.00.2919.6600 Dear Xav It depends whether you are looking for organic or inorganic solids. The Cambridge Crystallographic Database contains a large number (140000+) of structures of organic crystals. There is also the inorganic crystal structure database (ICSD) for inorganic solids. Both of these should be available from you national centre. David ******************************************************************************** Phone: 0207 409 2992 (Work) Dr. D.S. Coombes 0207 670 2934 (Voicemail) The Royal Institution of Great Britain 07958 677156 (Mobile) 21 Albemarle Street Fax: 0207 629 3569 London W1S 4BS Email davidc@ri.ac.uk Mobile email: davecoombes@sms.genie.co.uk (Less than 160 characters) ****************Registered Charity No. 227938**************************** ----- Original Message ----- From: To: Sent: 01 August 2000 07:57 Subject: CCL:Crystallography Database > Dear CCLers, > > I am looking for a (as cheap as possible!) database which > contains fractional coordinates of various solids. > That is because I found a paper in Acta Cryst., where the > authors give only some distances, angles, space group, > cell parameters,...but no fractional coordinates. > I really don't know how to built a crystal without frac. coor. > > Yours. > > ...Xav > > Ast. Pr. Xavier Assfeld Xavier.Assfeld@lctn.u-nancy.fr > Laboratoire de Chimie theorique (T) 33 3 83 91 21 49 > Universite Henri Poincare (F) 33 3 83 91 25 30 > F-54506 Nancy BP 239 http://www.lctn.u-nancy.fr > > -= 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 Tue Aug 1 10:36:10 2000 Received: from ne059.cm.utexas.edu (ne059.cm.utexas.edu [146.6.145.59]) by server.ccl.net (8.8.7/8.8.7) with SMTP id KAA25180 for ; Tue, 1 Aug 2000 10:36:10 -0400 Received: from ne057.cm.utexas.edu by ne059.cm.utexas.edu (AIX 3.2/UCB 5.64/4.03) id AA09994; Tue, 1 Aug 2000 09:29:59 -0500 Message-Id: <3986FB1F.38006858@eeyore.cm.utexas.edu> Date: Tue, 01 Aug 2000 09:30:23 -0700 From: "Isaac B. Bersuker" X-Mailer: Mozilla 4.7 [en] (WinNT; I) X-Accept-Language: en,zh,zh-CN,zh-TW Mime-Version: 1.0 To: MChalla@LANL.Gov, peo@compchem.dfh.dk, chemistry@ccl.net Subject: Re: CCL:TM force fields References: <39823A46.37BBE83A@studentergaarden.dk> <3985A906.DF449838@eeyore.cm.utexas.edu> <00073114171305.29864@ice> Content-Type: text/plain; charset=koi8-r Content-Transfer-Encoding: 7bit Dear Matt: The open (or quasi-open) d shell is the main reason of peculiar properties of TM systems (TMS) with regard to modeling: (1) 3D delocalization and hence strong mutual influence of the M-L bonds on each other (e.g., cis- and trans-effect), (2) "back donation" and hence local excitation of the ligands (chemical activation by coordination), (3) degeneracy and pseudodegeneracy and hence the strong Jahn-Teller and pseudo JT effects. All this together makes imposible to get reasonable parametrization of a force field (with transferable parameters) that could be used in modeling similar to that of organic and/or non-TMS, in general. I am sorry that these important features of TMS remain unknown to people engaged in their investigation. With Regards Isaac Matt Challacombe wrote: > Hi Isaac, > > Some how, I missed the begining of this thread, that is the main > criticisms. Seems to me you don't get transferability because of > nearly degenerate states that are highly dependent on external fields. > Is this most of it, or is there more? > > Cheers, Matt > > On Mon, 31 Jul 2000, you wrote: > > The point is that just the transferability does not work in TM compounds. > > There is no sense to continue the discussion until you reply specifically to the criticism > > of the force field idea in application to TM systems given, e.g., in the references I > > mentioned in my message: "... see see in Internat J. Quant. Chem. 1997,63,1051, and in > > Combined QM and MM Methods, Ed. J.Gao, M.A.Thompson, ACS Symposium Series 712, Washington > > 1998, pp 99-91". > > > > Regards > > I. B. > > > > Kasper Planeta Jensen wrote: > > > > > Dear Dr. Bersuker > > > > > > I reckon that transferability of parameters like bond distances, > > > (coordination-)geometries etc. > > > is not limited to the field of organic chemistry. Metal-ligand distances, force > > > constants, > > > torsion barriers etc. are similar in similar complexes. Hence, you can parameterize for > > > inorganic > > > compounds in the same way as for organic compounds. As long as transferability exists > > > in chemistry, force fields are possible that are not ad hoc per definition since they > > > generalize > > > this transfereability in terms of parameters. > > > > > > Yours, > > > Kasper > > > > > > "Isaac B. Bersuker" wrote: > > > > > > > Dear Dr. Norrby: > > > > > > > > Instead of getting iritated and offended, you better respond to the specific > > > > criticism of the force field idea in application to TM systems. This is SCIENCE, > > > > let me remind you, and the main condition of its progress is open discussion and > > > > proof of statements. I proved my statements in the references I gave earlier (that > > > > you deleted) and I would expect you to show that my proof is wrong. Just stating > > > > that one made calculations with good results does not prove anything, with > > > > arbitrary parameters (changed from one compound to another) everybody can get any a > > > > priori desired results. > > > > > > > > And, please, don't reffer to "authorities". I respect them all and their point of > > > > view, but the scientific truth is more important. > > > > > > > > Regards > > > > Isaac > > > > > > > > Per-Ola Norrby wrote: > > > > > > > > > Isaac B. Bersuker wrote: > > > > > > > > > > >I repeat my firm conviction that, in general, there are > > > > > >no force fields for transitiom metal systems (see my latest book ... > > > > > > > > > > (The rest of the message deleted). > > > > > > > > > > I've seen this comment a couple of times now, and I'm getting > > > > > irritated. This is a very sweeping statement, and insulting to those > > > > > who have produced good work in this area. It is only true if you > > > > > interprete it like "it is not possible to achieve infinite accuracy > > > > > for all possible TM complexes", but stated like that it would be > > > > > equally true of any method. For specific classes of complexes, it is > > > > > possible to get high accuracy with force field methods. It's just a > > > > > question of having a flexible enough force field and doing a careful > > > > > parameterization. Check out the book by Comba and Hambley, > > > > > "Molecular Modeling of Inorganic Compounds", a new edition is comming > > > > > out soon. We also have a review in press in Coord.Chem.Rev. on how > > > > > to do this parameterization (don't know when it's going to appear). > > > > > For some classical reviews, see: > > > > > > > > > > C.R. Landis, D.M. Root, T. Cleveland, in: K.B. Lipkowitz and D.B. > > > > > Boyd (Eds.), Reviews in Computational Chemistry, Vol. 6, VCH > > > > > Publishers, Inc., New York, 1995, p. 73-148. > > > > > > > > > > M. Zimmer, Chem. Rev. 95 (1995) 2629. > > > > > > > > > > P. Comba, Comments Inorg. Chem. 16 (1994) 133. > > > > > > > > > > B.P. Hay, Coordination Chemistry Reviews 126 (1993) 177. > > > > > > > > > > (Yes, I know, I left several out, this is just a selection based on > > > > > personal preference). > > > > > > > > > > The general force fields are also advancing. You can still > > > > > get whooping errors, and should validate carefully, but I've actually > > > > > been surprised several times by the results you can get without > > > > > specific parameterization. I'd like to point to UFF (not all > > > > > implementations though :-), VALBOND (not a complete force field, but > > > > > a very interesting addition to UFF), and the force fields in PCModel > > > > > and Spartan. There are others, but I don't have personal experience > > > > > with them. > > > > > > > > > > Per-Ola > > > > > -- > > > > > > > > > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > > > > * Per-Ola Norrby, Associate Professor > > > > > * The Royal Danish School of Pharmacy, Dept. of Med. Chem. > > > > > * Universitetsparken 2, DK 2100 Copenhagen, Denmark > > > > > * Tel. +45-35306506, fax +45-35306040 > > > > > * Email: peo@dfh.dk (preferred), peo@compchem.dfh.dk > > > > > * WWW: http://compchem.dfh.dk/PeO/ > > > > > > > > > > > > > -- > > > > Isaac B. Bersuker > > > > Institute for Theoretical Chemistry > > > > Department of Chemistry & Biochemistry > > > > The University of Texas at Austin > > > > Austin, TX 78712, USA > > > > Ph: (512) 471-4671 > > > > Fax: (512) 471-8696 > > > > Email: bersuker@eeyore.cm.utexas.edu > > > > > > > > > > > -- > > Isaac B. Bersuker > > Institute for Theoretical Chemistry > > Department of Chemistry & Biochemistry > > The University of Texas at Austin > > Austin, TX 78712, USA > > Ph: (512) 471-4671 > > Fax: (512) 471-8696 > > Email: bersuker@eeyore.cm.utexas.edu > > > > > > > > > > -= 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 > -- > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > + Matt Challacombe, Ph.D. http://www.t12.lanl.gov/~mchalla/ + > + Los Alamos National Laboratory email: mchalla@t12.lanl.gov + > + Theoretical Division pager: (505) 949-0096 + > + Group T-12, Mail Stop B268 phone: (505) 665-5905 + > + Los Alamos, New Mexico 87545 fax: (505) 665-3909 + > + + > + "The secret to mountain biking is pretty simple. The slower you go + > + the more likely it is you'll crash." -- Julie Furtado + > +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -- Isaac B. Bersuker Institute for Theoretical Chemistry Department of Chemistry & Biochemistry The University of Texas at Austin Austin, TX 78712, USA Ph: (512) 471-4671 Fax: (512) 471-8696 Email: bersuker@eeyore.cm.utexas.edu From chemistry-request@server.ccl.net Tue Aug 1 13:50:59 2000 Received: from drew.berry.edu (drew.berry.edu [168.31.232.19]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id NAA26467 for ; Tue, 1 Aug 2000 13:50:57 -0400 Received: from fsgw.berry.edu (fsgw.berry.edu [168.31.232.96]) by drew.berry.edu (8.9.3/8.9.3) with SMTP id NAA22888 for ; Tue, 1 Aug 2000 13:50:41 -0400 Received: from [168.31.235.19] ([168.31.235.19]) by fsgw.berry.edu; Tue, 01 Aug 2000 13:50:23 -0400 User-Agent: Microsoft-Outlook-Express-Macintosh-Edition/5.02.2022 Date: Tue, 01 Aug 2000 13:50:22 -0400 Subject: Calculating heats of formation From: Gary Breton To: Message-ID: Mime-version: 1.0 Content-type: text/plain; charset="US-ASCII" Content-transfer-encoding: 7bit Hello all, Please have patience with this computational newbie! I have need to calculate the heat of formation of a series of azo compounds. Previous papers suggest that the STO-3G ab initio level is sufficient for reasonable values. However, minimization (using HyperChem 5) affords a Total Energy for the system (in kcal/mol) that I need to convert to a heat of formation. My initial (albeit naive?) attempt utilizing tabulated standard enthalpies of the constituent atoms gave outrageously incorrect answers. I would appreciate any help on the matter. Many thanks in advance, Gary W. Breton Assoc. Professor Department of Chemistry Berry College PO Box 495016 Mount Berry, GA 30149 gbreton@berry.edu From chemistry-request@server.ccl.net Tue Aug 1 15:57:18 2000 Received: from goshen.rutgers.edu (0@goshen.rutgers.edu [165.230.180.150]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id PAA27282 for ; Tue, 1 Aug 2000 15:57:18 -0400 Received: from eden.rutgers.edu (molly.envsci.rutgers.edu [165.230.5.148]) by goshen.rutgers.edu (8.8.8/8.8.8) with ESMTP id PAA05361 for ; Tue, 1 Aug 2000 15:57:17 -0400 (EDT) Message-ID: <39872EF5.CE1128A4@eden.rutgers.edu> Date: Tue, 01 Aug 2000 16:11:34 -0400 From: "Mary O'Connor" X-Mailer: Mozilla 4.08 [en] (Win98; I) MIME-Version: 1.0 To: chemistry@ccl.net Subject: re:heats of formation Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Hello Gary and all CCLers: I tried doing ab initio heats of formation using HyperChem, and spoke to their support group. The HyperChem group told me that their software does not calculate ab initio heats of formation. Even by analyzing the vibrations, you cannot get a read out of the proper parameters to obtain the heat of formation. Gaussian does give a read out of these parameters. I'd be more specific, but I don't currently have a copy of the Gaussian manual, which can be purchased separately from the package. This has been my experience with ab initio heats of formation using HyperChem; others may be able to help you more. You might call the HyperChem support group to see if you can modify the calculate heat of formation script to constrain the geometry you get using ab initio method and apply either the AM1 or PM3 semi-empirical methods. My experience with using STO-3G for a geometry optimization of a molecule is that it gave me a much different structure than a STO 6-31G*. I am also a computational newbie, so please take my well-meant observations with as many grains of salt as you feel are appropriate! Best wishes; Mary O'Connor Rutgers University New Brunswick, NJ From chemistry-request@server.ccl.net Tue Aug 1 14:53:12 2000 Received: from hotmail.com (f293.law10.hotmail.com [64.4.14.168]) by server.ccl.net (8.8.7/8.8.7) with SMTP id OAA26971 for ; Tue, 1 Aug 2000 14:53:11 -0400 Received: (qmail 30719 invoked by uid 0); 1 Aug 2000 18:50:48 -0000 Message-ID: <20000801185048.30718.qmail@hotmail.com> Received: from 128.97.139.222 by www.hotmail.com with HTTP; Tue, 01 Aug 2000 11:50:48 PDT X-Originating-IP: [128.97.139.222] From: "eric hu" To: chemistry@ccl.net Subject: antibody homology Date: Tue, 01 Aug 2000 11:50:48 PDT Mime-Version: 1.0 Content-Type: text/plain; format=flowed Hi, I'm a newcomer to this field and wonder if someone can give me some hints how to build the antibody structure based on the homology with other known antibody that have x-ray crystal structure. I'm extremely interested in the related software such as AbM. With regards, -Eric ________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com From chemistry-request@server.ccl.net Tue Aug 1 15:45:13 2000 Received: from hermes.iupui.edu (hermes.iupui.edu [134.68.220.31]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id PAA27229 for ; Tue, 1 Aug 2000 15:45:13 -0400 Received: from macgw.chem.iupui.edu (macgw.chem.iupui.edu [134.68.137.71]) by hermes.iupui.edu (8.9.3/8.9.3/1.2IUPUIPO) with SMTP id OAA30368; Tue, 1 Aug 2000 14:45:05 -0500 (EST) Message-ID: Date: 1 Aug 2000 15:00:52 -0500 From: "Boyd" Subject: re: Calculating heats of formation To: "Breton, Gary" , "OSC CCL" X-Mailer: Mail*Link SMTP for Quarterdeck Mail; Version 4.1.0 Hi Gary, Check out the new chapter by L. A. Curtiss, P. C. Redfern, and D. J. Frurip, in Reviews in Computational Chemistry, K. B. Lipkowitz and D. B. Boyd, Eds., Wiley-VCH, New York, 2000, Vol. 15, pp. 147-211. Theoretical Methods for Computing Enthalpies of Formation of Gaseous Compounds. This chapter explains how to compute heats of formation at the ab initio, semiempirical, and empirical levels. Thanks, Don Donald B. Boyd, Ph.D. Editor, Reviews in Computational Chemistry http://chem.iupui.edu/rcc/rcc.html Editor, Journal of Molecular Graphics and Modelling (publication of the ACS COMP division and MGMS) http://chem.iupui.edu/~boyd/jmgm.html Department of Chemistry Indiana University-Purdue University at Indianapolis 402 North Blackford Street Indianapolis, Indiana 46202-3274, U.S.A. Telephone 317-274-6891, FAX 317-274-4701 E-mail boyd@chem.iupui.edu From chemistry-request@server.ccl.net Tue Aug 1 16:22:21 2000 Received: from neon.ch.pwr.wroc.pl (neon.ch.pwr.wroc.pl [156.17.3.51]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id QAA27455 for ; Tue, 1 Aug 2000 16:22:20 -0400 Received: from neon.ch.pwr.wroc.pl (localhost [127.0.0.1]) by neon.ch.pwr.wroc.pl (980427.SGI.8.8.8/970903.SGI.AUTOCF) via SMTP id WAA09831 for ; Tue, 1 Aug 2000 22:23:13 +0200 (MDT) Sender: jola@neon.ch.pwr.wroc.pl Message-ID: <398731B1.15FB@neon.ch.pwr.wroc.pl> Date: Tue, 01 Aug 2000 22:23:13 +0200 From: Jolanta Grembecka Organization: Wroclaw University of Technology X-Mailer: Mozilla 3.01SGoldC-SGI (X11; I; IRIX 6.3 IP32) MIME-Version: 1.0 To: chemistry@ccl.net Subject: CHELP charges Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Hallo all, Is it possible to calculate CHELP atomic charges fot the compound containing boron atom? I have tried to do it, but I have obtained in the output file the message: ----- Francl (CHELP) atomic radii used. Atom Element Radius 1 7 1.67 2 6 1.81 3 5 0.00 GetVDW: no radius for atom 3 atomic number 5. Error termination via Lnk1e in /d2/PROGRAMY/g98/l602.exe. ----- Third atom is boron. I would be grateful for help. Jolanta Grembecka -- *************************************** * Jolanta Grembecka * * Institute of Organic Chemistry, * * Biochemistry and Biotechnolgy * * Wroclaw University of Technology * * ul. Wybrzeze Wyspianskiego 27 * * 50-370 Wroclaw * * Poland * *************************************** From chemistry-request@server.ccl.net Tue Aug 1 16:24:09 2000 Received: from mum.mans.eun.eg (mum.mans.eun.eg [193.227.50.2]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id QAA27468 for ; Tue, 1 Aug 2000 16:24:00 -0400 Received: by mum.mans.eun.eg with Internet Mail Service (5.5.2650.21) id ; Tue, 1 Aug 2000 23:10:31 +0300 Message-ID: <4EF2E03A9B67D2119E2E0000F8053499427422@mum.mans.eun.eg> From: Tarek Mamoun El-Gogary To: "'CHEMISTRY@ccl.net'" Subject: Gamess question Date: Tue, 1 Aug 2000 23:10:22 +0300 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2650.21) Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01BFFBF4.8ADD1580" 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. ------_=_NextPart_001_01BFFBF4.8ADD1580 Content-Type: text/plain; charset="windows-1256" Content-Transfer-Encoding: quoted-printable Dear ccl=92s, Could any Gamess users, kindly, let me know what is the key word for = the basis set HF/6-31G** to be inserted in the input file. Thanks=20 Tarek El-gogary Ddept of Chem. Fac. of Sci. Mans. Univ. Egypt.=20 ------_=_NextPart_001_01BFFBF4.8ADD1580 Content-Type: text/html; charset="windows-1256" Content-Transfer-Encoding: quoted-printable Gamess question

Dear ccl=92s,

Could any Gamess users, kindly,  let = me know what is the key word for the basis set HF/6-31G** to = be inserted in the input file.

Thanks

Tarek = El-gogary

Ddept of Chem.

Fac. of Sci.

Mans. Univ.

Egypt.

------_=_NextPart_001_01BFFBF4.8ADD1580-- From chemistry-request@server.ccl.net Tue Aug 1 19:20:41 2000 Received: from email.nist.gov (email.nist.gov [129.6.2.7]) by server.ccl.net (8.8.7/8.8.7) with ESMTP id TAA28434 for ; Tue, 1 Aug 2000 19:20:41 -0400 Received: from silyl (silyl.nist.gov [129.6.194.163]) by email.nist.gov (8.9.3/8.9.3) with SMTP id TAA27865 for ; Tue, 1 Aug 2000 19:20:39 -0400 (EDT) Message-Id: <3.0.5.32.20000801191943.00b55380@mailserver.nist.gov> X-Sender: rdj3@mailserver.nist.gov X-Mailer: QUALCOMM Windows Eudora Pro Version 3.0.5 (32) Date: Tue, 01 Aug 2000 19:19:43 -0400 To: CHEMISTRY@ccl.net From: Russ Johnson Subject: re:Calculating heats of formation Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Hello, I would like to mention a resource that may help a little. The NIST computational chemistry comparison and benchmark database (CCCBDB)(at http://srdata.nist.gov/cccbdb ) allows a user to compare enthalpies of reaction and enthalpies of atomization for ab initio methods (about 18 methods and 9 basis sets). It has results for about 600 small (6 or fewer heavy atoms). It does not (yet) have any calculations using the STO-3G basis set or any molecule as large as an azo species. A semi-empirical method may be a better choice for heats of formation rather than an ab initio method with a minimal basis set. The CCCBDB has results from semiempirical methods (AM1, PM3) if you would like to compare to some calculated and experimental enthalpies (or experimental and calculated geometries) at those levels of theory. Dr. Russell D. Johnson III Research Chemist National Institute of Standards and Technology Computational Chemistry Group 100 Bureau Drive, Stop 8380 Gaithersburg, MD 20899-8380 voice 301+975-2513 fax 301+869-4020 email: russell.johnson@nist.gov From chemistry-request@server.ccl.net Tue Aug 1 21:26:42 2000 Received: from bilbo.edu.uy (bilbo.edu.uy [164.73.160.1]) by server.ccl.net (8.8.7/8.8.7) with SMTP id VAA29036 for ; Tue, 1 Aug 2000 21:26:39 -0400 Received: from localhost by bilbo.edu.uy (AIX 3.2/UCB 5.64/4.03) id AA26301; Tue, 1 Aug 2000 22:26:11 -0300 Date: Tue, 1 Aug 2000 22:26:11 -0300 (GRNLNDST) From: "Oscar N. Ventura" Reply-To: "Oscar N. Ventura" To: Russ Johnson Cc: CHEMISTRY@ccl.net Subject: Re: CCL:re:Calculating heats of formation In-Reply-To: <3.0.5.32.20000801191943.00b55380@mailserver.nist.gov> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Just my $ 0.02: The method of choice for calculating enthalpies of formation of any reasonably large molecule is DFT. Provided that one can write an isodesmic reaction for the molecule of interest, basis sets as modest as 6-31G(d) can give good results. If no such reaction can be written, then one can use the atomization reactions. In this case, CCSD(T) with Dunning basis would be preferable (provided that the calculations could be done) and corrections for core correlation, spin-orbit and relativistic effects must be included. Look up papers by Martin, Bauschlicher, Lee and others. BTW, IMHO a STO-3G calculation will give meaningless results. Oscar. ------------------------------------------------------------------------------- Prof.Dr.Oscar N. Ventura Tel.+(5982)9248396 Fax +(5982)9241906 MTC-Lab,Facultad de Quimica MTC-Lab http://bilbo.edu.uy/MTC-Lab.html Universidad de la Republica Gral.Flores 2124, C. C. 1157 All opinions are my own, and not Montevideo 11800, URUGUAY necessarily those of my employer "Violence is the last refuge of the incompetent." --- Salvor Hardin -------------------------------------------------------------------------------