COSMO solvation model: Difference between revisions

Revision as of 14:09, 10 May 2018

Revision as of 21:37, 3 July 2019

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From the thus determined solvent charges ''q'' and the known charge distribution of the molecule, the energy of the interaction between the solvent and the solute molecule can be calculated.

The COSMO method can be used for all methods in [[theoretical chemistry]] where the charge distribution of a molecule can be determined, for example semiempirical calculations, [[Hartree&ndash;Fock]]-method calculations or [[density functional theory]] (quantum physics) calculations.<ref name=":0">{{cite journal |last=A.|first=Klamt|last2=G.|first2=Schüürmann|date=1993|title=COSMO: a new approach to dielectric screening in solvents with explicit expressions for the screening energy and its gradient|url=http://pubs.rsc.org/en/content/articlepdf/1993/p2/p29930000799|journal=J. Chem. Soc.|publisher=Perkin Trans.2|volume=2|issue=5|pages=799–805|doi=10.1039/P29930000799|access-date=25 October 2015}}</ref>

==Variants and implementations==

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While models based on the [[multipole expansion]] of the charge distribution of a molecule are limited to small, quasi-spherical or ellipsoidal molecules, the COSMO method has the advantage that it can be applied to large and irregularly formed molecular structures.

In contrast to the polarizable continuum model (PCM), which uses the exact dielectric boundary conditions, the COSMO method uses the approximative scaling function f(''&epsilon;''). Though the scaling is an approximation, it turned out to provide a more accurate description of the so-called outlying charge, reducing the corresponding error. A method comparison<ref name=":2">{{Cite journal|last=Klamt|first=A.|last2=Moya|first2=C.|last3=Palomar|first3=J.|date=2015|title=A Comprehensive Comparison of the IEFPCM and SS(V)PE Continuum Solvation Methods with the COSMO Approach|doi=10.1021/acs.jctc.5b00601|journal=Journal of Chemical Theory and Computation|volume=11 |issue=9|pages=4220–4225|viaurl=https://zenodo.org/record/1451619}}</ref> of COSMO and the integral equation formalism PCM (IEFPCM), which combines the exact dielectric boundary conditions with a reduced outlying charge error, showed that the differences between the methods are small as compared to deviations to experimental solvation data. The errors introduced by treating a solvent as a continuum and thus neglecting effects like hydrogen bonding or reorientation are thus more relevant to reproduce experimental data than the details of the different continuum solvation methods.

==See also==