ROLE OF SOLUTE ELECTRONIC POLARIZABILITY IN SOLVATION DYNAMICS

Equilibrium and nonequilibrium solvation dynamics for a diatomic dipol ar solute in water are studied via molecular dynamics (MD) computer si mulations. The solute electronic structure;variation and associated po larizability are effected by a two-state description. This allows the instantaneous readjustment of the solute dipole moment to the fluctuat ing solvent environment. It is found that the solute polarizability ha s several striking consequences for solvation. Both inertial and diffu sive solvation dynamics become significantly slower as the solute pola rizability increases; the relative contribution to overall solvation f rom the inertial dynamics becomes markedly;reduced, Another novel feat ure is that the dynamics along the Franck-Condon energy gap coordinate -widely employed in many MD studies of solvation-become dependent on t he relative dipole character of the ground and excited electronic stat es, as well as on their relative polarizability difference. It is also found that the validity of Linear response becomes considerably limit ed when the solute is polarizable.