From chemistry-request@server.ccl.net Fri Jul 28 21:53:49 2000 Received: from lion.studentergaarden.dk (qmailr@[130.226.169.130]) by server.ccl.net (8.8.7/8.8.7) with SMTP id VAA01097 for ; Fri, 28 Jul 2000 21:53:48 -0400 Received: (qmail 9054 invoked from network); 29 Jul 2000 01:58:25 -0000 Received: from unknown (HELO studentergaarden.dk) (172.16.15.92) by nero.studentergaarden.dk with SMTP; 29 Jul 2000 01:58:25 -0000 Message-ID: <39823A46.37BBE83A@studentergaarden.dk> Date: Sat, 29 Jul 2000 03:58:30 +0200 From: Kasper Planeta Jensen X-Mailer: Mozilla 4.73 [en] (Win98; I) X-Accept-Language: en MIME-Version: 1.0 To: "Isaac B. Bersuker" CC: Per-Ola Norrby , chemistry@ccl.net Subject: Re: CCL:TM force fields References: <397C5C3F.28DEEEDA@eeyore.cm.utexas.edu> <3981EB26.6F70A956@eeyore.cm.utexas.edu> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit 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 > > -= 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 Sat Jul 29 23:25:20 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 XAA07799 for ; Sat, 29 Jul 2000 23:25:20 -0400 Received: from [128.211.130.255] by herald.cc.purdue.edu with ESMTP; Sat, 29 Jul 2000 22:25:13 -0500 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Message-Id: Date: Sat, 29 Jul 2000 22:23:10 -0800 To: chemistry@ccl.net From: Eric Scerri Subject: Foundations of Chemistry Web Pages I think I omitted to give the journal web page in my earlier posting Here it is now at the end of my signature section. Eric Scerri PhD, Visiting Professor, Department of Chemistry, Purdue University, West Lafayette, IN 47907 USA tel: 765 496 1992 -------------------------------------------------------------- Editor: Foundations of Chemistry, An Interdisciplinary journal for Philosophical, Historical and Educational Aspects of Chemistry. http://www.wkap.nl/journals/foch