COMP 54 |
| The D-COSMO-RS model, an extension of the original COSMO-RS [2] “Conductor like screening model for real solvents” approach, has been developed recently. In the normal COSMO-RS concept the quantum chemical COSMO [1] calculations for solutes and solvents are used as a reference state. In a next step the surface interactions of solutes and solvents, i.e. the electrostatic deviations from the conductor limit, as well as hydrogen bond interactions, are quantified using the polarization charge densities σ of neighboring segments as descriptors. Finally the chemical potentials of solutes and solvents are derived from a post-SCF statistical thermodynamics treatment. While this concept has proven to be very successful for the calculation of chemical potentials, it is not capable of providing any information about the response of the solute wave function on the presence of a specific solvent, and hence it cannot be used for the prediction of specific solvation effects on molecular properties as geometries, dipole moments, spectra, etc. Technically these properties can be treated on the continuum dielectric solvation level, but this level is theoretically inappropriate at least for polar solvents, and it is unable to take into account specific hydrogen bonding interactions. Thus it was a challenging idea to use the effective solvent response functions μ S(σ;T) arising from COSMO-RS directly in a quantum chemical SCF calculation. Since this method will avoid the indirect calculations by a conductor-SCF followed by post-SCF COSMO-RS, we call this approach “Direct COSMO-RS” or D-COSMO-RS. The theoretical basis of the model and first applications to solvent effects on geometries and on electronic g-tensors [3] will be given. [1] Klamt, A.; Schüürmann, G. Perkin. Trans. , 799-805 (1993). [2] Klamt, A. J. Phys. Chem. ,99 , 2224-2235 (1995). [3] Sinnecker, S.; Rajendran, A.; Klamt, A.; Diedenhofen, M.; Neese, F; J. Phys. Chem. A 110, 2235 -2245 (2006). |
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General Oral: Quantum Chemistry
1:00 PM-5:00 PM, Sunday, 10 September 2006 Moscone Center -- Room 208/210, Oral
Division of Computers in Chemistry |