From angel@fluor.quimica.uniovi.es Thu Sep 11 06:23:28 1997 Received: from fluor.quimica.uniovi.es for angel@fluor.quimica.uniovi.es by www.ccl.net (8.8.3/950822.1) id GAA17657; Thu, 11 Sep 1997 06:14:13 -0400 (EDT) Received: (from angel@localhost) by fluor.quimica.uniovi.es (8.6.12/8.6.9) id MAA16235 for chemistry@www.ccl.net; Thu, 11 Sep 1997 12:12:42 +0200 Date: Thu, 11 Sep 1997 12:12:42 +0200 From: Angel Martin Pendas Message-Id: <199709111012.MAA16235@fluor.quimica.uniovi.es> To: chemistry@www.ccl.net Subject: Band Structure code Dear CCLers, I am interested in obtaining reasonable analytical periodic electron densities of simple metals (Li, Ca, etc) in order to apply Bader's formalism to pure metallic crystals. However, it seems quite difficult to find any solid state physics code that uses some flavor of Plane Wave expansion. Could anyone inform me about any (freeware, shareware, etc) code or package meeting my needs? -- \|/ |^.^| ----OOO--\_/--OOO------------------------------------------------------ | Oh, The cheapness of mindless Angel Martin Pendas | calculation in modern age Professor of Chemistry | Dpto. Quimica Fisica y Analitica. | Roger Penrose, Univ. de Oviedo | The Emperor's new mind 33006 Oviedo. SPAIN | ----------------------------------------------------------------------- e-mail: angel@fluor.quimica.uniovi.es angel@carbono.quimica.uniovi.es voice: (int) 34 8 5103037 fax: (int) 34 8 5103125 www: http://www.uniovi.es/~quimica.fisica/qcg/amp/amp.html ----------------------------------------------------------------------- From MOLEC-98@bristol.ac.uk Thu Sep 11 09:23:30 1997 Received: from dirc.bris.ac.uk for MOLEC-98@bristol.ac.uk by www.ccl.net (8.8.3/950822.1) id IAA18137; Thu, 11 Sep 1997 08:43:05 -0400 (EDT) Received: from zeus.bris.ac.uk by dirc.bris.ac.uk with SMTP-PRIV (PP) with ESMTP; Thu, 11 Sep 1997 13:43:01 +0100 Received: from pc47.chm.bris.ac.uk (pc47.chm.bris.ac.uk [137.222.40.47]) by zeus.bris.ac.uk (8.8.7/8.8.4) with SMTP id NAA14303 for ; Thu, 11 Sep 1997 13:42:54 +0100 (BST) From: MOLEC Sender: molec@bristol.ac.uk To: Computational Chemistry List Subject: MOLEC conference Message-ID: Date: Thu, 11 Sep 1997 13:46:41 +0100 () Priority: NORMAL X-Mailer: Simeon for Win32 Version 4.0.9 X-Authentication: none MIME-Version: 1.0 Content-Type: TEXT/PLAIN; CHARSET=US-ASCII MOLEC XII Conference Bristol, UK, 6-11 September 1998 Preliminary announcement The 12th European Conference on Low Energy Molecular Collisions will be held in Bristol, UK, from 6 to 11 September 1998. Requests to be included in the conference mailing list may be made through the conference Web page (http://www.tlchm.bris.ac.uk/molec/molec.htm). The Web page will be updated periodically as the program is finalised. Professor J.C. Polanyi has agreed to give a keynote lecture at the conference. For further details contact Gabriel Balint-Kurti (Gabriel.Balint-Kurti@Bristol.ac.uk). From harry@chem.QueensU.CA Thu Sep 11 13:23:31 1997 Received: from post.queensu.ca for harry@chem.QueensU.CA by www.ccl.net (8.8.3/950822.1) id NAA19494; Thu, 11 Sep 1997 13:08:51 -0400 (EDT) Received: from chem.QueensU.CA (CHEM.QueensU.CA [130.15.98.1]) by post.queensu.ca (SMI-8.6/its9707) with SMTP id NAA26393 for ; Thu, 11 Sep 1997 13:09:09 -0400 (envelope from harry@chem.QueensU.CA) Received: by chem.QueensU.CA (4.1/SMI-4.0) id AA01419; Thu, 11 Sep 97 13:16:18 EDT Date: Thu, 11 Sep 97 13:16:18 EDT From: harry@chem.QueensU.CA (Igor Shamovsky) Message-Id: <9709111716.AA01419@chem.QueensU.CA> To: CHEMISTRY@www.ccl.net Subject: Coordination complexes. Hi netters, Could you please provide me with recent references concerning ab initio calculations of coordination complexes of transition metal cations, preferably those which have biological implications? Thanking you in advance, Igor. From toukie@zui.unizh.ch Wed Sep 10 03:23:14 1997 Received: from zzmkgtw.zzmk.unizh.ch for toukie@zui.unizh.ch by www.ccl.net (8.8.3/950822.1) id CAA11804; Wed, 10 Sep 1997 02:37:53 -0400 (EDT) Received: by zzmkgtw.zzmk.unizh.ch; (5.65v3.2/1.3/10May95) id AA26727; Wed, 10 Sep 1997 08:37:53 +0200 Message-Id: <3.0.3.32.19970910084021.00688270@highdent> X-Sender: toukie@highdent (Unverified) X-Mailer: QUALCOMM Windows Eudora Light Version 3.0.3 (32) Date: Wed, 10 Sep 1997 08:40:21 +0200 To: chemistry@www.ccl.net From: "Hr. Dr. S. Shapiro" Subject: MOPAC Question: Summary Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Dear Colleagues, Some time ago I submitted a question regarding how to do a MOPAC 6.0 run on p-tolylacetylene, which has four atoms [C(ar)-C#C-H] all in a straight line. I am grateful for the plethora of responses that I received. Very briefly, four suggestions were made: (a) use the normal Z-matrix, just add "xyz" to the list of keywords. This didn't work. Maybe it's a quirk in the Win95 port of MOPAC 6.0 that I use, but when I tried this strategy the calculation aborted with an error msg. to the effect that the programme was very unhappy with C(ar)-C#C-H = 180 degrees. (b) alter the Z-matrix so that C(ar)-C#C-H =/= 180 degrees at the start of the calculation. Sorry, but my port of MOPAC wasn't fooled by this. As soon as the geometry found itself adjusted to C(ar)-C#C-H = 180 degrees, it was no-go. (c) alter the geometry of the C(ar)-C#C-H unit using dummy atoms. Indeed, this works, but I was hoping for a slightly simpler solution that playing around with dummy atoms if I could possibly help it. (d) use Cartesian coordinates as the input. This was the solution I ultimately adopted. I drew the desired structure using PCModel and saved it as a normal MOPAC Z-matrix. I converted the input to Cartesian coordinates using Babel 1.6 for DOS and very slightly edited it to make it compatible with my port of MOPAC. It ran it with my "normal" roster of keywords; I did _not_ need to include "xyz" for the programme to recognise that the input was in Cartesian coordinates or that the calculation was to proceed using Cartesian coordinates. When I did this, the calculation quickly came to the desired conclusion. Again, many thanks to the respondents who were generous enough to share their experience and expertise with me. Regards, S. Shapiro toukie@zui.unizh.ch P.-S.: A summary re my LUMO question is pending. From toukie@zui.unizh.ch Wed Sep 10 04:23:16 1997 Received: from zzmkgtw.zzmk.unizh.ch for toukie@zui.unizh.ch by www.ccl.net (8.8.3/950822.1) id DAA11988; Wed, 10 Sep 1997 03:40:03 -0400 (EDT) Received: by zzmkgtw.zzmk.unizh.ch; (5.65v3.2/1.3/10May95) id AA30422; Wed, 10 Sep 1997 09:40:00 +0200 Message-Id: <3.0.3.32.19970910094229.00688270@highdent> X-Sender: toukie@highdent (Unverified) X-Mailer: QUALCOMM Windows Eudora Light Version 3.0.3 (32) Date: Wed, 10 Sep 1997 09:42:29 +0200 To: chemistry@www.ccl.net From: "Hr. Dr. S. Shapiro" Subject: LUMO<0: Summary Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Dear Colleagues; Many thanks for the people who cared to respond to my query re the physical interpretation of values of LUMO<0. Here is a very edited summary of the responses I rec'd: LUMO<0 is sometimes encountered when the MOPAC calc'n falls into a shallow well and yields a false optimal geometry. By Koopmans' theorem, the LUMO energy is _very_ approximately related to the electron affinity (EA). When LUMO<0, the molecule is electron-deficient and stabilised through acquisition of an electron; on the other hand, if LUMO>0 the molecule is destabilised by acquisition of an electron. The LUMO (and other low-lying orbitals) of cations is usually <0. Molecules for which LUMO<0 are good electron acceptors in redox systems, and the LUMO energy correlates well with experimental redox potentials. Because of rough parallels that exist between LUMOs and electron affinities or reduction potentials for a series of related compounds, LUMOs can be useful in QSPR formulations. If LUMO<0, then it constitutes a non-bonding molecular orbital, as in the case of aniline or phenol. When LUMO<0, "LUMO electrons" are formally involved in bonding, e.g., benzene in which the LUMO is a bonding pi-orbital. When LUMO>0, this orbital has antibonding character. Koopmans' theorem is not only roughly right in quantifying HOMOs and ionisation potentials, and is mostly wrong in quantifying LUMOs and EAs. Different Hamiltonians in semi-empirical calculations and different basis sets in ab initio calculations can give not only different magnitudes but different signs for LUMO energies. It is dangerous to assign too much significance to either signs or magnitudes of isolated orbitals; it is better to rely on trends of orbital properties across a set of molecules rather than on the properties of a single orbital in a single molecule. One person explicitly remarked that it is sometimes assumed (from the responspes I rec'd, that should be "usually assumed") that since Koopmans' theorem approximately equates HOMOs with IPs, then this theorem also approximately equates LUMOs with EAs. According to this respondent, this is not true; examination of the theoretical justification for Koopmans' theorem shows that it should _not_ apply to LUMOs. Comments and/or criticisms of this summary should _NOT_ be directed to me, but rather to the whole CCL readership. Regards, S. Shapiro toukie@zui.unizh.ch From Oliver.Kroehl@Uni-Koeln.DE Wed Sep 10 04:23:23 1997 Received: from rs1.rrz.Uni-Koeln.DE for Oliver.Kroehl@Uni-Koeln.DE by www.ccl.net (8.8.3/950822.1) id EAA12013; Wed, 10 Sep 1997 04:10:13 -0400 (EDT) Received: (from acp94@localhost) by rs1.rrz.Uni-Koeln.DE (8.8.5/8.8.6) id KAA48674; Wed, 10 Sep 1997 10:09:48 +0200 Date: Wed, 10 Sep 1997 10:09:45 +0200 (MST) From: Oliver Kroehl To: Rochus Schmid cc: chemistry@www.ccl.net Subject: Re: CCL:Summary: dispersion interactions In-Reply-To: <9709081940.ZM7839@felix> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Content-Transfer-Encoding: QUOTED-PRINTABLE Hello CCl=B4ers, dear Rochus, A very interesting book about molecular gas dynamics, the simulation of=20 gas flows and the different kinds of interaction in the gas stream at=20 different pressures and temperatures is: Molecular Gas Dynamics and the=20 Direct Simulation of Gas Flows, G. A. Bird, Oxford Engineering Science=20 Series 42, Oxford Science Publications, Clarendon Press, Oxford, 1994. Best Regards Oliver =20 On Mon, 8 Sep 1997, Rochus Schmid wrote: >=20 > Dear netters: >=20 > My original question was: >=20 > ******* > from my poor textbook knowledge I rmemeber, that the dispersion interacti= on > between e.g. rare gas atoms is something like a "induced dipole- induced > dipole" interaction and it follows -1/r^6. Right? > It is a "correlation" effect, thus, it doesn't appear in HF-calcs. >=20 > can someone point me to a ref. or explain me the origin in more detail? A= nd are > there any methods to somehow extract the amount of dispersion interaction > energy from post-HF calcs.? (or is this a stupid idea?) > ******* >=20 > Thanks to Jon Erickson, Guido Germano, Heinz Schiffer, Hayes Williams, Ma= rtin > Kaupp and Bernd Kallies. >=20 > Here a list of references (from H. Schiffer) >=20 > ********* > =09A. D. Buckingham > =09Basic theory of intermolecular forces: > =09Applications to small molecules > =09in: B. Pullmann (ed.), Intermolecular Interactions, > =09From Diatomics to Biopolymers, Wiley, New York 1978, > =09Chp.1, pp 1-67 >=20 > =09P. Claverie > =09Elaboration of approximate formulas for the interaction > =09between large molecules: Applications in organic chemistry > =09in: B. Pullmann (ed.), Intermolecular Interactions, > =09From Diatomics to Biopolymers, Wiley, New York 1978, > =09Chp. 2, pp. 69-305 >=20 > =09Bogumil Jeziorski, Robert Moszynski, Krzysztof Szalewicz > =09Perturbation Theory Approach to Intermolecular Potential > =09Energy Surfaces of van der Waals Complexes > =09Chem. Rev. 94 (1994) 1887-1930 >=20 > =09Sandor Kristyan, Peter Pulay > =09Can (semi)local density functional theory account > =09for the London dispersion forces ? > =09Chem. Phys. Lett. 229 (1994) 175-180 >=20 > =09Jose M. Perez-Jorda, A. D. Becke > =09A density-functional study of van der Waals forces: > =09rare gas diatomics > =09Chem. Phys. Lett. 233 (1995) 134-137 >=20 > =09Evert Jan Meijer, Michiel Sprik > =09A density-functional study of the intermolcular > =09interactions of benzene > =09J. Chem. Phys. 105(19) (1996) 8684-8689 >=20 > =09Michiel Sprik > =09Ab intio molecular dynamics simulation of liquids and > =09solutions > =09J. Phys.: Condens. Matter 8 (1996) 9405-9409 >=20 > =09Daxu Yin, Alexander D. MacKerell, Jr. > =09Ab initio Calculations on the Use of Helium and Neon as > =09Probes of the van der Waals Surfaces of Molecules > =09J. Phys. Chem. 100 (1996) 2588-2596 >=20 > =09Joerg-R. Hill > =09Use of Test Particle Calculations for the Derivation of > =09van der Waals Parameters Used in Force Fields > =09J. Comput. Chem. 18(2) (1007) 211-220 > ********* >=20 > Additionally from H. Williams: >=20 > *********** > Symmetry-Adapted Perturbation Theory (SAPT) is a method for finding the > interaction energy between two closed-shell ground state atoms or > molecules directly (as a post-HF computation). This interaction energy > includes the dispersion energy as one of its components. The major > reference to this work is: >=20 > B. Jeziorski, R. Moszynski, and K. Szalewicz, Chem. Rev. v94, p1887 > (1994). >=20 > I haven't seen the printed version yet, but the next major review > article will be: >=20 > K. Szalewicz and B. Jeziorski, > in {\em Molecular Interactions -- From van der Waals to Strongly > Bound Complexes}, edited by S. Scheiner, Wiley 1996. >=20 > One of my first applications of this work was to the Ar-H_2 system in: > J. Chem. Phys., v98, p1279 (1993). SAPT has been used to investigate > He_2, Ar-HF, He-HF, He-CO, He-C_2H_2 and a few others which I don't > have at my fingertips at the moment. Also, there is a large body of > theoretical work on the subject as well. >=20 > The SAPT codes are freely available from Dr. Szalewicz (email: > szalewic@udel.edu), but they are research level quality and may require > some tinkering on your part. > **************** >=20 > Thanks to all who replied. > Cheers >=20 > Rochus >=20 >=20 > --=20 >=20 > *************************************************************************= ******* > Dr. Rochus Schmid > Technische Universitaet Muenchen=09Tel. =09++49 89 2891 3385 > Lehrstuhl f. Anorganische Chemie 1=09Fax. =09++49 89 2891 3473 > Prof. W. A. Herrmann=09=09=09E-mail:=09 > Lichtenbergstrasse 4=09=09=09rochus@felix.anorg.chemie.tu-muenchen.de > 85747 Garching > *************************************************************************= ******* >=20 >=20 > --- > Administrivia: This message is automatically appended by the mail explode= r: > CHEMISTRY@www.ccl.net: Everybody | CHEMISTRY-REQUEST@www.ccl.net: Coordin= ator > MAILSERV@www.ccl.net: HELP CHEMISTRY or HELP SEARCH | Gopher: www.ccl.net= 73 > Anon. ftp: www.ccl.net | CHEMISTRY-SEARCH@www.ccl.net -- archive search > Web: http://www.ccl.net/chemistry.html=20 > --- >=20 >=20 From ccl@www.ccl.net Wed Sep 10 10:29:59 1997 Received: from bedrock.ccl.net for ccl@www.ccl.net by www.ccl.net (8.8.3/950822.1) id IAA12879; Wed, 10 Sep 1997 08:49:55 -0400 (EDT) Received: from nz11.rz.uni-karlsruhe.de for Joachim.Schummer@geist-soz.uni-karlsruhe.de by bedrock.ccl.net (8.8.6/950822.1) id IAA00465; Wed, 10 Sep 1997 08:49:53 -0400 (EDT) Received: from ips01 (actually ips01.geist-soz.uni-karlsruhe.de) by nz11.rz.uni-karlsruhe.de with SMTP (PP); Wed, 10 Sep 1997 14:44:05 +0200 Message-ID: <3417142C.515@geist-soz.uni-karlsruhe.de> Date: Wed, 10 Sep 1997 14:42:04 -0700 From: Joachim Schummer Reply-To: Joachim.Schummer@geist-soz.uni-karlsruhe.de Organization: Institute of Philosophy, University of Karlsruhe X-Mailer: Mozilla 3.01Gold [de] (Win16; I) MIME-Version: 1.0 To: CHEMISTRY list Subject: HYLE-Philosophy of Chemistry/New Issue Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Dear Members of CHEMISTRY: A new issue of --------------------------------------------------------- HYLE An International Journal for the Philosophy of Chemistry --------------------------------------------------------- is now available with full online text at: http://www.uni-karlsruhe.de/~philosophie/hyle.html HYLE is distributed non-commercially. If you have an interest in philosophical topics of chemistry, you are recommended to subscribe to HYLE (free of charge!), in order to receive regular informations off-list. The new issue contains articles from: Roald Hoffmann, Barry K. Carpenter (Ithaca, USA), Vladimir I. Minkin (Rostov-on-Don, Russia): "Ockham's Razor and Chemistry" Klaus Mainzer (Augsburg, Germany): "Symmetry and Complexity - Fundamental Concepts of Research in Chemistry" Giuseppe Del Re (Napoli, Italy): "Technology and the Spirit of Alchemy" Daniel Rothbart (Fairfax, USA), Irmgard Scherer (Baltimore, USA): "Kant's Critique of Judgment and the Scientific Investigation of Matter" Joachim Schummer (Karlsruhe, Germany): "Challenging Standard Distinctions between Science and Technology: The Case of Preparative Chemistry" F. Michael Akeroyd (Bradford, UK): "Conceptual Aspects of Theory Appraisal: Some Biochemical Examples" Klaus Ruthenberg (Coburg, Germany):"Short Biography: Friedrich Adolf Paneth" as well as book reviews and reports. --------------------------------------------------------- Dr. Joachim Schummer Institute of Philosophy, University of Karlsruhe Postfach 69 80, D-76128 Karlsruhe, GERMANY Joachim.Schummer@geist-soz.uni-karlsruhe.de From Regis.Gautier@univ-rennes1.fr Tue Sep 9 09:23:06 1997 Received: from mailimailo.univ-rennes1.fr for Regis.Gautier@univ-rennes1.fr by www.ccl.net (8.8.3/950822.1) id IAA06861; Tue, 9 Sep 1997 08:53:43 -0400 (EDT) From: Received: from daniels.univ-rennes1.fr (daniels.univ-rennes1.fr [129.20.128.26]) by mailimailo.univ-rennes1.fr (8.8.5/jtpda-5.2) with SMTP id OAA27035 for ; Tue, 9 Sep 1997 14:53:30 +0200 (MET DST) Message-Id: <199709091253.OAA27035@mailimailo.univ-rennes1.fr> X-Authentication-Warning: mailimailo.univ-rennes1.fr: daniels.univ-rennes1.fr [129.20.128.26] didn't use HELO protocol To: CHEMISTRY@www.ccl.net Subject: CCl:Benchmarks Date: Tue, 09 Sep 97 14:54:43 +0200 Dear CCL'ers, I'd like to know if any benchmarks for Gaussian94, ADF and ADF_BAND, WIEN95 and WIEN97, on parallel machine (IBM SP2, SGI,...) exist. Thanks for your help. Regis Gautier -------------------------------------------------------------- Regis GAUTIER, Laboratoire de Chimie du Solide et Inorganique Moleculaire, U.M.R. C.N.R.S 6511, Campus de Beaulieu 35042 Rennes Cedex, France. E-mail: rgautier@univ-rennes1.fr -------------------------------------------------------------- From ccl@www.ccl.net Tue Sep 9 13:41:45 1997 Received: from bedrock.ccl.net for ccl@www.ccl.net by www.ccl.net (8.8.3/950822.1) id NAA08431; Tue, 9 Sep 1997 13:11:28 -0400 (EDT) Received: from msuvx1.memphis.edu for tcundari@cc.memphis.edu by bedrock.ccl.net (8.8.6/950822.1) id NAA12898; Tue, 9 Sep 1997 13:11:22 -0400 (EDT) Received: from [141.225.145.9] by MSUVX1.MEMPHIS.EDU (PMDF V5.1-8 #16781) with SMTP id <01INFSG77BXS8X3AI6@MSUVX1.MEMPHIS.EDU> for chemistry@ccl.net; Tue, 9 Sep 1997 12:10:30 CST Date: Tue, 09 Sep 1997 12:10:22 -0600 From: tcundari@cc.memphis.edu (Tom Cundari) Subject: Re: CCL:RELATIVITY IN COMP CHEM To: "E. Lewars" Cc: chemistry@ccl.net Message-id: MIME-version: 1.0 Content-type: text/plain; charset="iso-8859-1" Content-transfer-encoding: quoted-printable Hello, Based on my experience with ECPs I can comment, most directly on questions 2) & 3) 2) ECPs are generally derived to model the potential generated by core electrons in an atom. If one starts with a Dirac-Fock calculation then the ECP models a 'relativistic' field. Likewise, if one starts with a Hartree-Fock calculation then a 'nonrelativistic' field is modeled by the ECP. In the ECPs developed by Stevens et al. all elements larger than Ne are generated from Dirac-Fock calculations. The use of relativistic calculations to generate the ECP is employed by Hay-Wadt (Rb and higher) and Ross et al. (Li and beyond). To my knowledge, most ECPs are derived empirically from atomic calculations and not adjusted to fit experimental data. I am not sure about the so-called "energy-adjusted ab initio pseudopotentials" from the Stuttgart group, but their works can be consulted for specifics. 3) Depends, of course, on what degree of accuracy you are looking for. For 'chemical' accuracy (prediction of geometries and some energetic quantities), my experience suggests that you probably do not have to worry about relativistic effects until the third transition series. For highly accurate 'spectroscopic' quantities (e.g., state-to-state transition energies) your surmise about the 4th period elements is probably correct. In my opinion, the best work on the use of ECPs to probe the importance of relativistic effects has been done by Schwerdtfeger & by the Stuttgart group. In their work, they cleverly use a combination of 'relativistic' & 'nonrelativistic' ECPs to probe the importance of relativistic effects. Some papers by Schwerdtfeger et al. are 38. a)J. Am. Chem. Soc., 111, 15 (1989). b) J. Am. Chem. Soc., 114, 7518 (1992). c) Organometallics, 9, 504 (1990). In the following paper by Dolg et al. they study CeO. An increase in bond length is seen upon inclusion of relativistic effects as opposed to the more common relativistic bond contraction. J. Chem. Phys., 90, 1730 (1989). =46or anyone interested in relativistic effects in chemistry, the reviews by Pyykko are classic. I think they remain the best intro to the topic for those with a 'chemical' interest in relativity. a) P. Pyykk=F6, Chem. Rev., 88, 563 (1988). Relativistic Effects in Structural Chemistry. b) P. Pyykk=F6, Adv. Quantum Chem., 11, 353 (1978). Relativistic Quantum Chemistry. >1997 Sept 9 > >Hello, > >Concerning the importance of the theory of relativity in computational >chemistry: > >1) Are there cases where the Dirac-Fock equation, rather than the Schroedi= nger > equation, should be used? >2) To what extent are the effective core potentials of ab initio > calculations derived empirically, to fit experiment, rather than > theoretically? >3) Where should you start using effective core potentials to simulate > relativistic effects --at which element does the error start becoming > significant (somewhere around element 33 to 37, I suspect--As, Se, Br, > Kr, Rb)? > > Thanks > > E. Lewars =3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+= =3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+ Tom Cundari Department of Chemistr= y Associate Professor The University of Memphis e-mail:tcundari@cc.memphis.edu Memphis, TN 38152-6060 phone: 901-678-2629 =46AX: 901-678-3447 http://www.chem.memphis.edu/umchem.html **** U of Memphis is conducting a search for an Assistant Professor of Computational Chemistry, contact me by email for details **** =3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D= +=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+=3D+ From iguana@one.net Tue Sep 9 22:23:11 1997 Received: from one.net for iguana@one.net by www.ccl.net (8.8.3/950822.1) id WAA11141; Tue, 9 Sep 1997 22:14:28 -0400 (EDT) Received: from shell.one.net (shell.one.net [206.112.192.106]) by one.net (8.8.6/2000AD) with ESMTP id WAA30443 for ; Tue, 9 Sep 1997 22:14:16 -0400 Received: from localhost (iguana@localhost) by shell.one.net (8.8.7/AD2000) with SMTP id WAA32008 for ; Tue, 9 Sep 1997 22:14:16 -0400 X-Authentication-Warning: shell.one.net: iguana owned process doing -bs Date: Tue, 9 Sep 1997 22:14:16 -0400 (EDT) From: Ray Crawford To: CHEMISTRY@www.ccl.net Subject: Re: CCL:NCI SMILES Database In-Reply-To: <199709092312.TAA15185@helix.nih.gov> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII All, Marc C. Nicklaus & Bruno Bienfait raised an interesting point... It is difficult to do string comparisons with SMILES... Does anyone know of any utilities available that can do this quickly and painlessly? Thanks, Ray Crawford The P&G Co.