From graham@sentex.net Sat Dec 2 01:54:51 1995 Received: from granite.sentex.net for graham@sentex.net by www.ccl.net (8.6.10/950822.1) id BAA09241; Sat, 2 Dec 1995 01:54:11 -0500 Received: from p20.silicon.sentex.ca (p20.silicon.sentex.ca [199.212.134.68]) by granite.sentex.net (8.6.12/8.6.9) with SMTP id BAA23376; Sat, 2 Dec 1995 01:58:12 -0500 Message-Id: <199512020658.BAA23376@granite.sentex.net> X-Sender: graham@mail.sentex.net X-Mailer: Windows Eudora Version 1.4.4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Sat, 02 Dec 1995 01:51:12 -0500 To: gadre@falcon.cdac.ernet.in, CHEMISTRY@www.ccl.net From: graham@sentex.net (Graham Hurst) Subject: Re: CCL:Buckingham-Fowler and Legon-Millen Models Shridhar R. Gadre wrote: >Dear Colleagues : >Could you send me a list of successes/failures of Buckingham-Fowler >as well as Legon-Millen models for studying weak intermolecular complexes? >One success, for instance is the reasonable geometry for the HCHO-HF complex >using the former. >Needless to say that I am more interested in failures! Thanks a lot. A decade ago I did ab initio calculations on all the known failures (that could calculated at the time) and some typical successes of the Buckingham-Fowler model. The results are in: G.J.B. Hurst, P.W. Fowler, A.J. Stone and A.D. Buckingham, "Intermolecular Forces in van der Waals Dimers", Int. J. Quantum Chem. vol 23, pp 1223-1239 (1986) There were several systems where the Buckingham-Fowler model had some trouble (but didn't necessarily fail): H2O/C2H2 H2O/CO2 HF/ClF CO2/HF CO2/H2O CO2/HCN These were cases where the use of hard spheres was a poor approximation or where the electrostatic interaction was relatively isotropic. The other systems I looked at were: NH3/HF N2O/HF H2CO/HF H2O/HF CH3CN/HCN More successes can be found in: A.D. Buckingham and P.W. Fowler, J. Chem. Phys. 79, 6426 (1983) A.D. Buckingham and P.W. Fowler, Can. J. Chem. 63, 2018 (1985) I recall more recent reviews on the subject by David Buckingham, but don't have them at hand... Cheers, Graham ------- Graham Hurst, PhD or Cambridge, Ontario, Canada From Y0H8797@ACS.TAMU.EDU Sat Dec 2 14:40:02 1995 Received: from VMS2.TAMU.EDU for Y0H8797@ACS.TAMU.EDU by www.ccl.net (8.6.10/950822.1) id OAA16606; Sat, 2 Dec 1995 14:39:39 -0500 Date: Sat, 2 Dec 1995 13:39:48 -0600 (CST) From: YONG HUANG To: CHEMISTRY@www.ccl.net Message-Id: <951202133948.2222e8d0@ACS.TAMU.EDU> Subject: (1)Koopman's Theorem and (2)BondingREAD/NEW (1) Can anyone tell me whether ionization potential calculated based on Koopman's Theorem is just the IP for vertical ionization? I suspect so because I think what Koopman's Theorem misses is just the vibrational relaxation in the ionic state after the electron is gone. Please correct me if I'm wrong. (2) I use CAChe MOAPC to calculate the distances and bond orders between the 3 hydrogens of a NH3 right above the pai ring of ferulic acid (4-OH-3-OCH3- cinnamic acid). After geometry optimization, NH3 shifts to the edge of the pai-ring. I did this calculation in 3 ways: 1) no bonding is specified between H's of NH3 and pai-ring; 2) 1 H of NH3 hydrogen-bonded to carbons #1,3,5 (if the 6 C's are numbered 1 to 6); 3) 3 H's of NH3 hydrogen-bonded to C's #1,3,5, respectively. My question is: Does the calculation take into account whether I specified the bonding at all? It seems it doesn't. The results always show small bond order between H's of NH3 and substituents of the ring AND EVEN SMALLER bond order between those H's of NH3 and C's of the ring, regardless of whether I draw hydrogen bond lines in the CAChe Editor (Graphic Interface for MOPAC). Seems MOPAC Input doesn't have bond information. I guess specifying bonds in Editor doesn't do anything at all. Can someone clarify this for me? Thank you very much. I'll summarize. Yong y0h8797@acs.tamu.edu From owner-chemistry@ccl.net Sat Dec 2 23:10:09 1995 Received: from bedrock.ccl.net for owner-chemistry@ccl.net by www.ccl.net (8.6.10/950822.1) id XAA22117; Sat, 2 Dec 1995 23:07:54 -0500 Received: from yfn2.ysu.edu for bo771@yfn.ysu.edu by bedrock.ccl.net (8.7.1/950822.1) id XAA27283; Sat, 2 Dec 1995 23:07:51 -0500 (EST) Received: (from bo771@localhost) by yfn2.ysu.edu id XAA01956 (8.6.12/IDA-1.6); Sat, 2 Dec 1995 23:08:32 -0500 Date: Sat, 2 Dec 1995 23:08:32 -0500 Message-ID: <199512030408.XAA01956@yfn2.ysu.edu> From: bo771@yfn.ysu.edu (Wayne Ward) To: CHEMISTRY@ccl.net Subject: chemistry Reply-To: bo771@yfn.ysu.edu Yes I was woungering if I could reiceive a catalog with the infor. and dealing of chemicals and chemistry items. If so please let me know by my e-mail adress bo771@yfn.ysu.edu Sincercley dewayne ward