The interaction potentials between the six lowest electronic states of I-2(-) and an arbitrary discrete charge distribution are calculated approximately using a one-electron model. The model potentials are much easier to calculate than ab initio potentials, with the cost of a single 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 dusters 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 strong electric field, the negative charge localizes so as to minimize the total potential energy. However, in a weak field the negative charge localizes 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 electron transfer.