Solvation of electronically excited I2−

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Abstract
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 I−2 in liquids and CO2 clusters is discussed. In a preliminary application, solvent effects are approximated by a uniform electric field. If electronically excited (2Πg,1/2) 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 2Πg,1/2I−2, in contrast to the conventional view of relaxation via electron transfer.