CCL:G: COSMO, CPCM, and COSMO-RS definitions

 Sent to CCL by: Andreas Klamt [klamt()]
 Dear CCLers,
 this morning I again got quite angry about two papers mixing up the term
 COSMO, CPCM, and COSMO-RS, and therefore I like to explain them here
 shortly again. Please try to use them correctly and cite them correctly,
 when you write your papers using one of these methods.
 - COSMO: The conductor-like screening model is the variant of the
 continuum solvation models, which uses a scaled conductor boundary
 condition instead of the much more complicated dielectric boundary
 condition for the calculation of the polarization charges of a molecule
 in a continuum. The correct reference is [A. Klamt, G. Schüürmann, J.
 Chem. Soc. Perkin Trans.2 (1993) 799]  COSMO has turned out to be
 computationally extremely efficient and robust, and to be less sensitive
 to outlying charge error. Therefore it has been implemented in in a wide
 range of quantum chemical codes. Please note that there are differences
 - mainly regarding the cavity construction and the radii defaults - in
 the various implementation, and specially between the implementations
 originating from my code and those originating from PCM or other codes.
 Nevertheless, I think all of them should be summarized under the
 expression COSMO. (It is important to note, that COSMO means a scaled
 conductor boundary condition, not a conductor itself, as often written
 in literature. It is not a conductor model, but a conductor-like model!)
 - CPCM is the implementation of COSMO in the PCM framework (V. Barone
 and M. Cossi, J. Phys. Chem. A 1998, 112, 1995ff), as most widely
 distributed and used in the Gaussian program. To be honest, I would be
 grateful if a citation to the original COSMO paper would be given as
 well when using CPCM or another re-implementation, because meanwhile 60%
 of the COSMO usages do not refer to COSMO anymore.
 - COSMO-RS (COSMO for real solvents, [1,2]) is a statistical
 thermodynamics post-processing of COSMO calculations, which I personally
 consider as the most physically sound continuum solvation model
 presently availably. It extends the applicability of quantum chemistry
 to the entire range of fluid phase thermodynamics, including mixtures
 and variable temperatures. COSMO-RS is based on COSMO calculations
 (COSMO files) for the individual solutes and solvents). COSMO-RS
 calculations require a COSMO-RS post-processing program, e.g. our
 COSMOtherm program. (Just for curiosity: I - as the inventor of COSMO -
 do not believe in the simple dielectric continuum solvation models at
 all, neither PCM nor COSMO. I am convinced that only by the RS extension
 a reasonable physics is put into these models. Therefore you will not
 find a single quantitative COSMO parameterization by me. Since 1994 I
 only work on COSMO-RS)
    1. [1] A. Klamt,  J. Phys. Chem. 99 (1995)  2224
    2. [2] A. Klamt, V. Jonas, T. Buerger, J.C.W. Lohrenz, J. Phys. Chem.
       102 (1998) 5074-5085
 - Since Gaussian03 there is (or there was - I am not absolutely sure
 about the latest sub-releases) a keyword COSMORS available in PCM.  This
 keyword has caused a lot of misuse. It was intended to trigger the right
 settings in PCM in order to produce COSMO files that can be used in
 COSMOtherm. But now many Gaussian users use this keyword and report the
 results as COSMO-RS calculations. This is absolutely wrong!!! These are
 CPCM calculations using the defaults optimized within COSMO-RS. By the
 way, even the term "KLAMT radii" has entered literature, since
 introduced the keyword "radii=KLAMT". I am not a fan of such
 personalization. Please use the expression "radii optimized for
 COSMO-RS" or "COSMO-RS radii" and use reference [2] for these
 Thanks for your help in avoiding more confusion
 Andreas Klamt
 P.S.: A rather complete description of COSMO and COSMO-RS is given in my
 recent book "COSMO-RS: From Quantum Chemistry to Fluid Phase
 Thermodynamcs and Drug Design", Elsevier, 2005
 Dr. habil. Andreas Klamt
 COSMOlogic GmbH&CoKG
 Burscheider Str. 515
 51381 Leverkusen, Germany
 Tel.: +49-2171-73168-1  Fax:  +49-2171-73168-9
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