SOLVATION OF ELECTRONICALLY EXCITED I-2(-)

The interaction potentials between the six lowest electronic states of I-2(-) and an arbitrary discrete charge distribution are calculated a pproximately using a one-electron model. The model potentials are much easier to calculate than ab initio potentials, with the cost of a sin gle energy point scaling linearly with the number of solvent molecules , enabling relatively large systems to be studied. Application of the model to simulation of electronically excited It in liquids and CO2 du sters is discussed. In a preliminary application, solvent effects are approximated by a uniform electric field. If electronically excited (( IIg,1/2)-I-2) I-2(-) undergoes dissociation in the presence of a stron g electric field, the negative charge localizes so as to minimize the total potential energy. However, in a weak field the negative charge l ocalizes in the opposite direction, maximizing the, potential energy. Based on a study of the field-dependent potential surfaces, a solvent- transfer mechanism is proposed for the electronic relaxation of (IIg,1 /2I2-)-I-2, in contrast to the conventional view of relaxation via ele ctron transfer.