Average solvent electrostatic configuration

Figure 7-14. Comparison between the statistical distribution and the average value obtained using the average solvent electrostatic configuration (central vertical line)...

According with experimental data, the n-n band of MOx is shifted by —2,145 90 cm (—0.266 0.011 eV) when the solvent changes from iso-octane to water [16] and extrapolated as —2,410 90 cm (—0.299 0.011 eV) from gas phase to water using a linear regression in the a plot of the experimental values for the maximum absorption transition energy, Emax. of the MOx in several solvent [16] versus the normalized Reichardt solvent polarity scale, Ej [2] (see Fig. 3). In order to discuss, the absorption spectrum of solute MOx (S) in water different theoretical representations of the solvent was adopted (1) the polarizable continuum model (S -I- PCM), which provides a simplified representation of the solvent as a continuum dielectric medium (2) the average solvent electrostatic configuration (S -I- ASEC), where 250 water molecules of... 

ASEP/MD, acronym for average solvent electrostatic potential obtained from molecular dynamics data, is a sequential QM/MM method that makes extensive use of the mean field approximation (MFA) [24], In solution, any static property A of the system must be calculated by averaging over the configurational space A defined by all the configurations thermally accessible to the system ... 

As the ASEC replaces the statistical distribution by just one average configuration it suppresses the statistical distribution. Hence one will not succeed in the study of inhomogeneous broadening and line width of the absorption spectra of liquid systems, for instance. But ASEC will be very efficient and accurate for obtaining average solute properties in the electrostatic field of the solvent. 

The second approach to the approximate description of the dynamic solvation effects is based on the semiempirical account for the time-dependent electrical polarization of the medium in the field of the solute molecule. In this case, the statistical averaging over the solute-solvent intennolecular distances and configurations is presumed before the solution of the SchrOdinger equation for the solute and correspondingly, the solvent is described as a polarizable dielectric continuum. The respective electrostatic solvation energy of a solute molecule is given by the following equation[13]... 

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