CALCULATION OF UV VIS SPECTRA IN SOLUTION

The adequate treatment of solvation effects in the calculation of UV/v is spectra is a complicated task and a general solution of this proble m is still outstanding. Continuum solvation models like COSMO at least allow one to take into account a large part of the different solvent effects on electronic excitations, if the dielectric screening is prop erly implemented within the CI part of the underlying MO program. A co mprehensive development of the respective theory is given. This ends u p in a rather simple result, and it turns out that most of the former approaches to the problem have been in severe error. Geometry changes of the solute in different solvents have been taken into account for t he first time and appear to be of considerable importance. A few examp le applications of a COSMO-MOPAC implementation are presented.