From chemistry-request -8 at 8- ccl.net Tue Nov 2 01:32:32 2004 Received: from mrbusi1.netcologne.de (mrbusi1.netcologne.de [194.8.194.213]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id iA26WTjA020260 for ; Tue, 2 Nov 2004 01:32:31 -0500 Received: from cosmologic.de (xdsl-213-196-221-180.netcologne.de [213.196.221.180]) by mrbusi1.netcologne.de (Postfix) with ESMTP id 8E11F1A0042; Tue, 2 Nov 2004 07:45:27 +0100 (CET) Message-ID: <41872D04.104:at:cosmologic.de> Date: Tue, 02 Nov 2004 07:45:24 +0100 From: Andreas Klamt User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.6b) Gecko/20031205 Thunderbird/0.4 X-Accept-Language: en-us, en MIME-Version: 1.0 To: "Deng, Jun" , CHEMISTRY:at:ccl.net Subject: Re: CCL:Thermal chemistry involves amino acid in H2O References: <3251EC702A37B9458A01D917C3D3B3890350DD:at:sgofusr20.nac.ppg.com> In-Reply-To: <3251EC702A37B9458A01D917C3D3B3890350DD:at:sgofusr20.nac.ppg.com> Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, hits=4.4 required=7.5 tests=MY_BAD_DOT,MY_DSL, RCVD_IN_DYNABLOCK,RCVD_IN_SORBS autolearn=no version=2.61 X-Spam-Checker-Version: SpamAssassin 2.61 (1.212.2.1-2003-12-09-exp) on servernd.ccl.net Dear Jun, amino acids in water obviously are complicated species because they typically exist as zwitterions. Hence for accurate thermochemistry you have to take those into account. The problem is that you need a very good level of quantum chemistry to get a good value for the energy difference of neutral and zwitterionic state, and then obviously also a good one for the difference between amino acids and the reaction products. I am afraid that coupled cluster methods may be required, if you can afford them. Perhaps you can do these as single points on DFT geometries. Thus I suggest that you first do the thermochemistry the gasphase. Then use our COSMOtherm program to get the solvation free energies of the educts and products. Thus you finally should end up at the thermochemistry in water. Regards Andreas Deng, Jun wrote: >Dear all: > >I am interested in calculating heat of reaction in water involving amino acid. May I ask your suggestion on how to get accurate result? > >Thank you very much in advance! > >Jun Deng > > > > > >-= This is automatically added to each message by the mailing script =- >To send e-mail to subscribers of CCL put the string CCL: on your Subject: line >and send your message to: CHEMISTRY:at:ccl.net > >Send your subscription/unsubscription requests to: CHEMISTRY-REQUEST:at:ccl.net >HOME Page: http://www.ccl.net | Jobs Page: http://www.ccl.net/jobs > >If your mail is bouncing from CCL.NET domain send it to the maintainer: >Jan Labanowski, jlabanow:at:nd.edu (read about it on CCL Home Page) >-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ > > > > > > > > -- -------------------------------------------------------------------------------- Dr. Andreas Klamt COSMOlogic GmbH&CoKG Burscheider Str. 515 51381 Leverkusen, Germany Tel.: +49-2171-73168-1 Fax: +49-2171-73168-9 e-mail: klamt:at:cosmologic.de web: www.cosmologic.de -------------------------------------------------------------------------------- COSMOlogic Your Competent Partner for Computational Chemistry and Fluid Thermodynamics --------------------------------------------------------------------------------