From chemistry-request $#at#$ server.ccl.net Fri Jul 12 09:34:59 2002 Received: from mail.fqspl.com.pl ([212.244.147.20]) by server.ccl.net (8.11.6/8.11.0) with SMTP id g6CDYxc27929 for ; Fri, 12 Jul 2002 09:34:59 -0400 Received: (qmail 31783 invoked from network); 12 Jul 2002 13:42:14 -0000 Received: from unknown (HELO test) (212.244.147.4) by mail.fqspl.com.pl with SMTP; 12 Jul 2002 13:42:14 -0000 Message-ID: <00de01c229a9$51c8c840$320a0a0a&$at$&test> From: "Victor Anisimov" To: References: <009901c2281b$46bb8e40$320a0a0a: at :test> Subject: Summary:Accuracy question Date: Fri, 12 Jul 2002 15:37:51 +0200 MIME-Version: 1.0 Content-Type: text/plain; charset="koi8-r" Content-Transfer-Encoding: 8bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 Dear CCLers, A couple of days ago I asked a question: > Based on my short investigation I could learn that HF/6-31G* is the most > popular method for electrostatic parameter optimization in Amber, Charmm, > OPLS and perhaps in other prominent force fields with the aim of the > description of molecular electrostatic potential of protein systems. > > Here I'd like to ask experts in this field. Is it the correct conclusion I > derived or perhaps other quantum-chemistry methods are more popular > for the purpose of electrostatic parameters development, e.g. databases > of ESP charges of amino acids or similar. I have got two replies. Many thanks to Prof. JoÇo Bosco Paraiso da Silva and to Dr. E. Lewars for sharing their opinion. The short summary is that HF/6-31G* is recommended for ESP charge fitting. Nevertheless HF/3-21G is also in use for calculation of molecular electrostatic potential of proteins and parameterization of the electrostatic components of the force field parameters. Additionally I could dig up that there is some interest to electrostatic property calculations by density functional GGA methods employing Coulomb density fitting procedure, although it is not clear how important (or non important) are errors due to not use of the explicit Hartree-Fock exchange. Any comments a very welcome. With best regards, Victor. -- Victor Anisimov FQS Poland, Krakow ================================================ From: "Bosco" > Do you know the paper: M.D. beachy et al JACS, 119,5908-5920(1997). > There you may find on page 5917 arguments why one should use HF/6-31G* > charges on molecular parametrization process. From: "elewars" > I think it makes little difference whether you use HF/6-31G* or the faster > HF/3-21G for electrostatic properties. Compare some test jobs. Since you use > programs like Amber and Charmm, I believe you are doing single-point > calculations on geometries obtained by MM.