From jan.hrusak@jh-inst.cas.cz Thu Apr 30 05:11 EDT 1998 Received: from fikus.jh-inst.cas.cz for jan.hrusak@jh-inst.cas.cz by www.ccl.net (8.8.3/950822.1) id FAA18409; Thu, 30 Apr 1998 05:11:15 -0400 (EDT) Received: from tracy.jh-inst.cas.cz (tracy.jh-inst.cas.cz [147.231.29.251]) by fikus.jh-inst.cas.cz (8.7.6/8.7.3) with ESMTP id LAA27504 for ; Thu, 30 Apr 1998 11:11:09 +0200 Received: from TRACY/SpoolDir by tracy.jh-inst.cas.cz (Mercury 1.40); 30 Apr 98 11:11:09 +0200 Received: from SpoolDir by TRACY (Mercury 1.40); 30 Apr 98 11:10:49 +0200 Received: from pc9101.jh-inst.cas.cz (147.231.29.101) by tracy.jh-inst.cas.cz (Mercury 1.40); 30 Apr 98 11:10:39 +0200 Received: by pc9101.jh-inst.cas.cz with Microsoft Mail id <01BD7428.EF290A40@pc9101.jh-inst.cas.cz>; Thu, 30 Apr 1998 11:12:59 +-200 Message-ID: <01BD7428.EF290A40@pc9101.jh-inst.cas.cz> From: Jan Hrusak To: "'CHEMISTRY-REQUEST@www.ccl.net'" , "'Jan Hrusak'" Subject: RE: QCISD energy lower than QCISD(T) energy! Date: Thu, 30 Apr 1998 11:12:58 +-200 Encoding: 28 TEXT Content-Type: text I would like to add also my contribution to the recent discussion on QCISD/QCISD(T). I have been using these methods for a quite long time. They became very popular due to the implementation into all (or almost all) of the QC programs. The wide use of the QCI methods is also due to the implementation and particular success of the G1/G2 methods. For many (gas phase) experimentalists the numbers produced by using the GAUSSIAN G2 keyword are a kind of final answer if the experimental data are not listed in standard data compilations. I am not saying, that G2 does not produce "good" numbers in most of the cases. However, examples documented (L. Radom) where even G2 energies are quite unreasonable. This could be atributed to the multireference character of the WF, wrong orbitals (T1 not close to 0), and/or to a simple failure of the QCISD method. The QCI is in the limit (i.e. T1=O) equal to the coupled cluster method (CC). For T1~0 the CC method is more stable than QCI. However, one should always check the T1 and T2 amplitudes and the T1 norm. Recently, we have investigated one of the cases where QCI gives unreasonable results while CC is still OK. (JCP 106 (1997) 7185) These cases demonstrate themself in big T1 (T2) amlitudes (and positive energy contributions of the pertubative triples in QCI). The QCISD gives seemingly correct results for the structure, energy, freqs etc. but the QCISD density (dipole moments!!) are qualitativelly wrong. QCISD(T) breaks down completely. In most of the QC programs the QCISD ist only marginaly more expensive than the corresponding CCSD and thus I do not see any reason for using the QCI method. In addition, in cases where the WF is not a strict single reference one the convergency of CCSD is superior to QCISD. Jan Hrusak From korkin@act.sps.mot.com Fri May 1 18:28:12 1998 Received: from spsem02.sps.mot.com for korkin@act.sps.mot.com by www.ccl.net (8.8.3/950822.1) id RAA28686; Fri, 1 May 1998 17:50:38 -0400 (EDT) Received: from mogate.sps.mot.com by spsem02.sps.mot.com (4.1/SMI-4.1/Email 2.1 10/25/93) id AA21518 for CHEMISTRY@www.ccl.net; Fri, 1 May 98 14:50:38 MST Received: from emailsps.sps.mot.com by mogate.sps.mot.com (4.1/SMI-4.1/Email-2.0) id AA20139 for CHEMISTRY@www.ccl.net; Fri, 1 May 98 14:50:36 MST Received: from zsneezy.sps.mot.com (korkin@zsneezy [223.189.20.100]) by sps.mot.com (8.8.6 (PHNE_14041)/8.8.6) with ESMTP id OAA22166 for ; Fri, 1 May 1998 14:50:35 -0700 (MST) From: Anatoli Korkin Received: (from korkin@localhost) by zsneezy.sps.mot.com (8.8.6/8.8.6) id OAA09243 for CHEMISTRY@www.ccl.net; Fri, 1 May 1998 14:50:34 -0700 (MST) Date: Fri, 1 May 1998 14:50:34 -0700 (MST) Message-Id: <199805012150.OAA09243@zsneezy.sps.mot.com> To: CHEMISTRY@www.ccl.net Subject: Project based mailing list: molecular mideling of silicon nitrdide films deposition, structure and properties X-Mailer: Siren Mail (Motif 2.02 95/05/15) Mime-Version: 1.0 Content-Id: <304_9227_894059434_1@zsneezy> Content-Type: text/plain; charset="us-ascii" Dear Colleagues, For one of our projects we are going to organize an e.mail based "discussion club". You are invited to join us if you are interested in the topic and feel able to contribute in discussions based on your experience and research in this field. The project concerns gas phase, surface and solid state chemistry (theoretical and experimental) of silicon nitride film preparation, namely chemical vapor deposition and related phenomena. The detailed molecular mechanism is of interest, as well as relations between "chemistry" and film properties at a molecular/atomic level. This "discussion forum" will start as my own personal e.mail group. Depending on the response, it may be kept in this form or converted to a separate automatically running mailing list. Additional tools, e.g. databases, web pages, electronic and "real life" workshops may be organized based upon how much interest, information and funding are available. Although we do not require any particular application/subscription form, you are welcome to send some information about yourself and your area of research. All questions and comments are welcome. Most frequently asked questions and answers will be posted to everyone who expresses interest in participating in the topic discussions. Feel free to forward this message to your colleagues, who may be interested to participate. You should understand that any information you submit will be freely distributed to others who have expressed an interest in this email based information exchange. Therefore, no confidential information should be submitted. By participating you agree that any information you submit will be considered in the public domain, even if marked as confidential, and that this information may be distributed to other members of this mailing group. Sincerely, Anatoli Korkin From kallies@serv.chem.uni-potsdam.de Thu Apr 30 09:27:55 1998 Received: from hp.rz.uni-potsdam.de for kallies@serv.chem.uni-potsdam.de by www.ccl.net (8.8.3/950822.1) id IAA19155; Thu, 30 Apr 1998 08:41:50 -0400 (EDT) Received: from serv.chem.uni-potsdam.de (serv.chem.uni-potsdam.de [141.89.160.2]) by hp.rz.uni-potsdam.de (8.8.8/8.8.8) with SMTP id OAA21970; Thu, 30 Apr 1998 14:41:03 +0200 (MESZ) Received: from pch10.chem.uni-potsdam.de by serv.chem.uni-potsdam.de (AIX 4.1/UCB 5.64/4.03) id AA20030; Thu, 30 Apr 1998 14:30:55 +0100 Message-Id: <35487265.5477AA0F@serv.chem.uni-potsdam.de> Date: Thu, 30 Apr 1998 14:45:25 +0200 From: Bernd Kallies X-Mailer: Mozilla 4.04 [en] (Win95; I) Mime-Version: 1.0 To:chemistry@www.ccl.net Subject: parm94 and glycam93 in AMBER Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit We are currently dealing with molecular mechanics calculations on proteins coupled with oligosaccharides. We decided to use an AMBER force field together with GLYCAM. The original GLYCAM paper (Woods et al, JPC 1995) said that this parameter set (called glycam93 in the AMBER program) was developed in agreement with the old AMBER force field (Weiner et al, JACS 1984, called parm91), but it might also be used with the new developed AMBER parameters (Cornell et al, JACS 1995, called parm94) because of the similar philosophy of assignment of atomic charges (both parm94 and glycam93 use RESP charges from HF/6-31G*, whereas parm91 used HF/STO-3G). Regarding to the coupling of glycam93 and parm94 we have several questions: 1. Does anybody know if these parameter sets should be coupled in principle? 2. If one can do so, which scaling factor of 1-4 nonbonding interactions should be used (0.5 as for parm91 and as used in Woods' paper for parameterization, or 0.83 as for parm94)? 3. The Woods paper refers to some parameters in the GLYCAM force field which were adopted from the parm91 parameter set. Should these parameters be used from parm91 also for the coupling with the parm94 set or should they be replaced by the new parm94 parameters, which are a bit different? Thank you for your assistance. Bernd Kallies -- Dr. Bernd Kallies University Potsdam Institute for Physical and Theoretical Chemistry Am Neuen Palais 10 14469 Potsdam GERMANY e-mail: kallies@serv.chem.uni-potsdam.de WWW : http://www.chem.uni-potsdam.de/~kallies/kallies.htm Tel : [+49] (0)331 / 977-1313 Fax : [+49] (0)331 / 977-1315