From owner-chemistry@ccl.net Fri May 19 06:25:00 2006 From: "Andreas Klamt klamt---cosmologic.de" To: CCL Subject: CCL: Parameters for PCM calculation Message-Id: <-31790-060519062248-25390-MKOnjLcvikrgO1t75/TkYQ:-:server.ccl.net> X-Original-From: Andreas Klamt Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-15 Date: Fri, 19 May 2006 12:22:39 +0200 MIME-Version: 1.0 Sent to CCL by: Andreas Klamt [klamt*_*cosmologic.de] Dear Ramon, you are right: almost all implicit solvation models are parameterized mainly for water and have a crude scaling for lower dielectric constants. You cannot expect that the specific details of a solvent as olive oil is reasonably quantitatively described by such implicit solvation method. I personally consider the change of te solvent radius according to the solvent as a very unphysical concept, and I doubt that there are any good rules how to set that radius. As far as I know, the only implicit solvation method that can deal with almost arbitrary solvent and solvents mixtures, even at variable temperatures without the need for any solvent information (not even the dielectric constant) is my COSMO-RS method. COSMO-RS describes solutes and solvents on the same quantum-chemical footing and brings them together by a statistical thermodynamics of interacting surfaces. For more details and lots of references see our homepage or my book "COSMO-RS: From quantum chemistry to fluid phase thermodynamics and drug design", Elsevier, 2005. Regards Andreas Ramon Crehuet rcsqtc..iiqab.csic.es schrieb: > Sent to CCL by: Ramon Crehuet [rcsqtc.:.iiqab.csic.es] > Dear CCLers, > I would like to do a PCM calculation using GAMESS and this program needs > some parameters for the solvent. I guess any software needs this > parameters. Ideally I should use olive oil as solvent, but ether has a > similar dielectric constant. > Precisely I don't know where to find the following properties: > * the solvent radius > * the thermal expansion coefficient > * the thermal coefficient of the surface tenstion > * the cavity microscopic coefficient > * solvent numeral density > * distances between the first atoms of each type and the cavity (can > this be just a guess or should this be calculated? And how?) > > I have the feeling that usually only water is used as a solvent and that > although the method in GAMESS is general, the solvent parameters for > other solvents are not trivial and,thus, other solvents are rarely used. > Has anybody experience with that? > Thanks for your attention, > Ramon Crehuet> > > > > > -- ----------------------------------------------------------------------------- Dr. habil. Andreas Klamt COSMOlogic GmbH&CoKG Burscheider Str. 515 51381 Leverkusen, Germany Tel.: +49-2171-73168-1 Fax: +49-2171-73168-9 e-mail: klamt(!)cosmologic.de web: www.cosmologic.de ----------------------------------------------------------------------------- COSMOlogic Your Competent Partner for Computational Chemistry and Fluid Thermodynamics -----------------------------------------------------------------------------