From owner-chemistry@ccl.net Wed Sep 18 04:12:27 1996 Received: from bedrock.ccl.net for owner-chemistry@ccl.net by www.ccl.net (8.7.5/950822.1) id DAA19607; Wed, 18 Sep 1996 03:24:26 -0400 (EDT) Received: from fstgds01.tu-graz.ac.at for hassler@ftug01.dnet.tu-graz.ac.at by bedrock.ccl.net (8.7.5/950822.1) id DAA13102; Wed, 18 Sep 1996 03:24:19 -0400 (EDT) From: Received: from FTUG01.DECnet MAIL11D_V3 by fstgds01.tu-graz.ac.at (5.57/Ultrix3.0-C) id AA23375; Wed, 18 Sep 96 09:24:03 +0200 Date: Wed, 18 Sep 96 09:24:03 +0200 Message-Id: <9609180724.AA23375@fstgds01.tu-graz.ac.at> To: FULTRX"chemistry@ccl.net"@ccl.net Subject: summary flexible molecules Dear members of CCL! Here is a summary to my question concerning IR of flexible molecules: I have two questions concerning vibrational spectroscopy (IR,Ra) of fluxional molecules. Problem 1: two conformers are separated by a transition barrier that is so small that the conformers are not distinguishable on the time scale of IR and Ra spectroscopy. One would then expect to observe average temperature dependent signals. But what happens if the two conformers belong to different molecular point groups with different selection rules?(eg. 1,2-disubstituted dislanes: XH2SiSiH2X gauche conformer: C2 (all vibrations IR and Ra active) anti conformer: C2h (Ag,Bg Ra active, Au,bu Ir active). How would variable temperature IR and Ra spectra behave in this case? Problem 2: ab initio theory finds two conformers on the potential energy surface of XH2SiSiH2X. the energy of the two gauche conformer(C2) lies a bit above the energy of the anti isomer(C2h). The zero point energy of the torsional motion that interconverts the two conformers is calculated to lie above the very small barrier of interconversion of the conformers. So there is clearly one set of torsional energy levels for this system. But what happens to the small amplitude vibrations? On the assumption that small amplitude vibrations are calculated to differ clearly for the two conformers- would one still see separated individual small amplitude modes for both conformers in the vibrational spectra or only those of the anti conformer (C2h) as the gauche conformer represents something like a `pseudominiumum`? Here are the answers; thanks to all those who replied! From: FULTRX::"rdj3@ENH.NIST.GOV" 12-SEP-1996 21:33:31.03 To: ftug01::hassler CC: Subj: floppy moelcules Hello, I have attempted to treat some floppy moelcules by explicity calculating the potential energy surface for the floppy modes, and calculating the vibrational frequencies >from the p.e.s. Specifically I've looked at CH2OH, which has a CH2 wag with a barrier below the zero point energy. I used floppy molecule group theory, as discussed in "Molecular Symemtry and Structure" by Philip R. Bunker, and ended up calling the molecule G4, as opposed to C2v or Cs or C1. G4 is isomorphic with C2v but how x,y, and z transform is different, giving rise to different IR selection rules. (I haven't looked at the RAMAN rules.) For something like H2XSiSiXH2 I'm not sure what the appropriate point group would be, when the torsion is allowed. I did try an AM1 frequency calculation of the anti and gauche forms of H2FCCFH2 and for the most part the IR vibrations that are not allowed in C2v are very weak in Cs. I would expect a similar situation for H2XSiSiXH2. Russ Russell D. Johnson III Research Chemist Physical and Chemical Properties Division National Institute of Standards and Technology Gaithersburg, MD 20899 voice 301+975-2513 fax 301+975-3670 email: russell.johnson@nist.gov From: FULTRX::"cory@bohr.chem.mun.ca" 10-SEP-1996 19:30:15.16 To: ftug01::hassler CC: Subj: ZPE energy and conformers. Please don't treat the following as gospel, but I recall reading somewhere that any potential well must have at least one bound vibrational state. This would suggest that all of the conformers you have examined independently have at least one bound state associated with them, which should give rise to at least three vibrational levels which would mix (related to 'inversion doubling') over all values of the torsional mode. What may be happening is that the potential is so anharmonic that the ZPE calculation is in significant error and is exceeding the classical barrier. With regards to the first problem, I believe permutation groups must be used in this analysis (Sorry I don't have a reference handy). -Cory ************* ***************** ! Cory C. Pye *** ** ** ** ! Graduate Student and Unpaid Sys Admin ** * **** ! Theoretical and Computational Chemistry ** * * ! cory@bohr.chem.mun.ca ** * * ! http://www.ucs.mun.ca/~cory/index.html *** * * ** ! ***************** ! Les Hartree-Focks ************* ! (Apologies to Montreal Canadien Fans) From: FSCM1::SMTP%"ComputationalChemistryList" 11-SEP-1996 22:37:52.04 To: hassler CC: Subj: CCL:FLUXIONAL MOLECULES 1996 Sept 11 hassler@ftug01.dnet.tu-graz.ac.at asked about conformational isomerism and IR/NMR. Hdere's my $0.01 worth. Hello, Sorry if I can't contribute too much to the solution of your problems, but I have two comments: (1) Fluxional molecules are systems like cycloheptatriene/norcaradiene, or bullvalene. The term fluxional is usually applied to molecules that participate in *valence tautomerism*, not to conformationally mobile molecules (of course, almost all molecules are conformationally mobile). (2) You say "Two conformers are...not distinguishable on the time scale of IR and Ra spectroscopy." In *NMR* spectroscopy it is common for conformationally mobile species to show at room temp. only an average set of NMR signals, but to display on cooling the peaks of the individual conformers. However, so far as I know the frequency of IR radiation is so much higher than that of radio waves that IR/Raman spectroscopy always takes snapshots of the individual conformers. The freq of rotation about single bonds is about 10**12 Hz (ca. 100 cm**-1), while IR radiation has a freq of ca. 10**13 Hz (ca. 1000 cm**-1). So IR does not see the individual conformers as a blur. For example, the IR of butane is a superimposition of the IR's of the gauche and anti conformers. Ich denke, Sie mu:ssen eine a:usserst niedrige Barrierre haben, wenn es nicht mo:glich ist, die individuelle Konformationen zu unterscheiden. === Errol Lewars ==== *) Mr. Tucker Jr. (Universite de Montreal) recommended the book `Molecular Symmetry and Spectroscopy` by P.R. Bunker for the basic understanding of spectroscopy of flexible molecules and permutation groups. Best wishes to everyone! Robert Zink Institut fuer Anorganische Chemie, Technische Universitaet Graz, Stremayrgasse 16 present e-mail: hassler@fscm1.tu-graz.ac.at From ingo@amethyst.Chemie.Uni-Dortmund.de Wed Sep 18 08:12:28 1996 Received: from mail.Germany.EU.net for ingo@amethyst.Chemie.Uni-Dortmund.de by www.ccl.net (8.7.5/950822.1) id HAA20594; Wed, 18 Sep 1996 07:39:18 -0400 (EDT) Received: by mail.Germany.EU.net with SMTP (5.59:24/EUnetD-2.5.4.c) via EUnet id NAA25781; Wed, 18 Sep 1996 13:39:16 +0200 Received: by amethyst.Chemie.Uni-Dortmund.de (AIX 3.2/UCB 5.64/OCB-loki-1.0-31011995) id AA18061; Wed, 18 Sep 1996 13:39:35 +0100 From: ingo@amethyst.Chemie.Uni-Dortmund.de (Ingo Koeper) Message-Id: <9609181239.AA18061@amethyst.Chemie.Uni-Dortmund.de> Subject: interaction of force constants To: chemistry@www.ccl.net Date: Wed, 18 Sep 1996 13:39:35 +0100 (NFT) X-Mailer: ELM [version 2.4 PL2] Content-Type: text My question is: do there exist a rule acording to the sign (plus or minus) of interacting force constants in a molecule? For examplein Water: Which is the force constant, that describes the interaction between bending and bonding? Ingo Koeper ingo@amethyst.chemie.uni-dortmund.de From choic@gusun.georgetown.edu Wed Sep 18 14:12:30 1996 Received: from gusun.acc.georgetown.edu for choic@gusun.georgetown.edu by www.ccl.net (8.7.5/950822.1) id NAA22647; Wed, 18 Sep 1996 13:42:54 -0400 (EDT) Received: from localhost by gusun.acc.georgetown.edu (SMI-8.6/SMI-SVR4) id NAA17533; Wed, 18 Sep 1996 13:37:51 -0400 Date: Wed, 18 Sep 1996 13:37:50 -0400 (EDT) From: Cheol Choi X-Sender: choic@gusun To: chemistry@www.ccl.net Subject: X Server for Quanta and Cerius2 ? Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Dear CCLers, We are using the Quanta and Cerius2 programs with the SGI workstations. Since there are a lot of users, we are considering having X Servers (usually PC based computer with Windows or Mac) with X terminal emulator. But we couldn't find any X terminal emulator which is DGL capable. Please, let us know a proper X terminal emulator if there is any especially for Quanta and Cerius2. Thank you. Cheolho Choi Dept. of Chem. Georgetown Univ. From netsci@awod.com Wed Sep 18 15:12:36 1996 Received: from sumter.awod.com for netsci@awod.com by www.ccl.net (8.7.5/950822.1) id OAA22808; Wed, 18 Sep 1996 14:28:48 -0400 (EDT) Received: from [198.81.225.45] (chs0126.awod.com [198.81.225.45]) by sumter.awod.com (8.6.12/8.6.12) with SMTP id OAA19025; Wed, 18 Sep 1996 14:28:45 -0400 X-Sender: arichon@awod.com Message-Id: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Wed, 18 Sep 1996 14:34:43 +0100 To: chemistry@www.ccl.net From: netsci@awod.com (Network Science) Subject: 1997 Charleston Conference Cc: netsci@awod.com Network Science Corporation announces The 1997 Charleston Conference: Advancing New Lead Discovery. The complete program with registration information is available at: http://www.awod.com/netsci/Meetings/charleston.html The invited lectures and round table discussions to be held at the March 3-5 meeting will focus on the successful integration of bioinformatics, combinatorial chemistry, high throughtput screening, computational chemistry and cheminformatics in new lead discovery and development. Monday, March 3, 1997 Opening Address Gerald Maggiora (Director of Computer-Aided Drug Discovery, Pharmacia & Upjohn) Bioinformatics Session Chair: Michael N. Liebman (Director, Bioinformatics and Genomics, Vysis, Inc.) * Michael W. Retsky (Associate Professor, University of Colorado; Scientific Director, OncoMetics, Inc.) * Frank Tobin (Assistant Director of Scientific Computing Consulting, SmithKline Beecham) * Michael N. Liebman (Director, Bioinformatics and Genomics, Vysis, Inc.) Lunch Break Combinatorial Chemistry Session Chair: Michael Pavia (Vice President, Cambridge Research, Sphinx Pharmaceuticals, A Division of Eli Lilly and Company) * William Hoekstra (Principal Scientist, RW Johnson Pharmaceutical Research Institute) * Stephen W. Kaldor (Head Combinatorial Chemistry, Lilly Research, Eli Lilly and Company) * Peter Myers (Chief Operating Officer, CombiChem, Inc.) * Alex Polinsky (Vice President and Chief Scientific Officer, Alanex Corporation) Dinner: A Taste of Charleston Tuesday, March 4, 1997 High Throughput Screening Session Chair: John P. Devlin (President, ARRT International; President and CEO, MicroBotanica, Inc.) * John Babiak (Associate Director Robotics and Automation, Wyeth-Ayerst Research Institute) * Jonathan Cook (Technical Manager, High Throughput Screening Group, Procter & Gamble) * Harry Stylli (Senior Director, Screening Technologies, Aurora BioSciences) Lunch Break Computational Chemistry Session Chair: Christine Humblet (Senior Director of the Biomolecular Structure and Drug Design Section, Parke-Davis Research, Warner-Lambert) * Bob McDowell (Senior Scientist, Genentech) * Dennis Underwood (Associate Director, Molecular Systems, Merck Research Laboratories) * Jean-Pierre Wery (Head, Computational Chemistry and Molecular Structure Research, Lilly Research Laboratories, Eli Lilly and Company) * Scott Dixon (Associate Director, SmithKline Beecham Pharmaceutical Research and Development) Round Table Discussions with Dinner Wednesday, March 5, 1997 Cheminformatics Session Chair: Allen B. Richon (Chief Science Officer, Network Science Corporation) * Jon S. Mason (Head of Computer-Assisted Drug Design, Rhone-Poulenc Rorer, Inc.) * Robert S. Pearlman (Coulter R. Sublett Regent's Chair in Pharmacy and Director Laboratory for Molecular Graphics and Theoretical Modeling, College of Pharmacy, University of Texas at Austin) * David Spellmeyer (Associate Director, Computational and Biophysical Chemistry Group, Chiron Corporation) Attendance for this meeting will be limited. Registration forms can be completed at the Network Science Web site or via e-mail, fax or US mail. Please contact Network Science (netsci@awod.com) with any questions about the meeting or to request an e-mail registration form. From qocruces@usc.es Wed Sep 18 16:12:32 1996 Received: from uscmail.usc.es for qocruces@usc.es by www.ccl.net (8.7.5/950822.1) id PAA23150; Wed, 18 Sep 1996 15:51:06 -0400 (EDT) Received: from qobrue.usc.es.usc.es (qobrue.usc.es) by uscmail.usc.es (5.67b/1.34) id AA22412; Wed, 18 Sep 1996 21:54:39 +0200 Date: Wed, 18 Sep 1996 21:54:39 +0200 Message-Id: <199609181954.AA22412@uscmail.usc.es> X-Sender: qocruces@uscmail.usc.es X-Mailer: Windows Eudora Version 1.4.4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: chemistry@www.ccl.net From: qocruces@usc.es (Jacobo Cruces) Subject: NMR simulation algorithms Dear Netters: We are very interested in fast algorithms for the simulation of spin systems in NMR, specially if the algorithms are just written in C or C++. We will appreciate any comment on bibliographic references. Thank you in advance. Jacobo Cruces Colado Department of Organic Chemistry University of Santiago de Compostela Avda. de las Ciencias s/n 15706 SPAIN e-mail: qocruces@uscmail.usc.es From pis_diez@nahuel.biol.unlp.edu.ar Wed Sep 18 18:12:33 1996 Received: from biol.unlp.edu.ar for pis_diez@nahuel.biol.unlp.edu.ar by www.ccl.net (8.7.5/950822.1) id RAA23604; Wed, 18 Sep 1996 17:17:02 -0400 (EDT) Received: from jubert.biol.unlp.edu.ar (jubert.biol.unlp.edu.ar [163.10.7.25]) by biol.unlp.edu.ar (8.6.9/8.6.9) with SMTP id RAA00374 for ; Wed, 18 Sep 1996 17:47:26 -0300 Date: Wed, 18 Sep 1996 17:47:26 -0300 Message-Id: <199609182047.RAA00374@biol.unlp.edu.ar> X-Sender: pis_diez@nahuel.biol.unlp.edu.ar X-Mailer: Windows Eudora Version 1.4.3 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: chemistry@www.ccl.net From: pis_diez@nahuel.biol.unlp.edu.ar (Reinaldo Pis Diez) Subject: Basis for DGauss and references Hi folks, I was looking for info on basis sets to use in LCGTO-based DFT methods, specially on the Gaussian Basis Sets Order Form. I've found basis of quality DZVP, DZVPP (or DZVP2) and TZVP there and the same reference is quoted for all of them: N Godbout, DR Salahub, J Andzelm and E Wimmer, Can J Chem 70 (1992) 560. However, when I tried this reference I've only found DZVPP basis and up to Ne, no more! Even the authors say in subsection 1.5, pp 561, "Subsequent papers will include basis sets for atoms through xenon." My question is: does anybody know of the existence of this "subsequent paper" and others if any? I'd appreciate any answers and will summarize to the net. Thanx in advance. Regards, Reinaldo From gaussian.com!moses@lorentzian.com Wed Sep 18 19:12:32 1996 Received: from relay5.UU.NET for gaussian.com!moses@lorentzian.com by www.ccl.net (8.7.5/950822.1) id SAA23759; Wed, 18 Sep 1996 18:16:19 -0400 (EDT) Received: from uucp2.UU.NET by relay5.UU.NET with SMTP (peer crosschecked as: uucp2.UU.NET [192.48.96.33]) id QQbhth00606; Wed, 18 Sep 1996 18:16:21 -0400 (EDT) Message-Id: Received: from m10.UUCP by uucp2.UU.NET with UUCP/RMAIL ; Wed, 18 Sep 1996 18:16:21 -0400 Received: by m10.lorentzian.com; Wed, 18 Sep 1996 18:16:15 -0400 Received: by mousse.gaussian.com; Wed, 18 Sep 1996 16:08:07 -0400 From: gaussian.com!moses@lorentzian.com (David Moses) Subject: Gaussian Workshop To: CHEMISTRY@www.ccl.net Date: Wed, 18 Sep 1996 16:08:06 -0400 (EDT) X-Mailer: ELM [version 2.4 PL24] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit ** Gaussian Workshop in Liege, Belgium, December 3-6 ** Gaussian, Inc. will be holding a workshop at Universite de Liege, Belgium December 3-6 of this year. This workshop will be cosponsored by Digital Equipment Corporation. The workshop "Introduction to Gaussian: Theory and Practice," will cover the full range of methods available in the Gaussian package with emphasis on new methods and features which make Gaussian applicable to an ever widening spectrum of research applications. Instructors for the workshop will include Dr. Mike Frisch and Dr. Doug Fox (Gaussian, Inc.), Dr. Mike Robb (King's College London), and Dr. George Petersson (Wesleyan University). The workshop is structured to provide an introduction to electronic structure theory as well as a hands-on review for researchers already active in the field. The workshop is open to researchers at all levels of academic, government and industrial research. The topics to be covered include the following: * Introduction to Electronic Structure Theory * Model Chemistries: A Framework for Understanding Electronic Structure Theory Results * Geometry Optimization Techniques * Electron Correlation Methods * Density Functional Theory Methods * Excited State via CI-Singles * Thermochemistry via Model Chemistries * Predicting Molecular Properties * Solvent Effects on Molecular Electronic Structure * Gaussian Utilities * Estimating Resource Requirements There will be hands-on sessions each day between the morning and afternoon lectures. Additional hands-on sessions may be available at other times. Workshop participants will be provided with access to a DEC workstation to complete exercises, experiment and/or conduct short research topics. Each workshop participant will also receive the course materials, the Gaussian 94 User's Reference and a copy of Exploring Chemistry with Electronic Structure Methods. The cost of the workshop is $250. For further details and application procedures, contact the workshop coordinator at Gaussian, Inc. at the phone, fax number or e-mail address given below. Best Regards, David *------------------------*------------------------*-----------------------* | David J. Moses, Ph.D. | Carnegie Office Park | info@gaussian.com | | Vice President, C.O.O. | Building Six | 412-279-6700 (Voice) | | Gaussian, Inc. | Pittsburgh, PA 15106 | 412-279-2118 (FAX) | *------------------------*------------------------*-----------------------* | Be sure to visit our Website at http://www.gaussian.com | *------------------------*------------------------*-----------------------*