One-electron model for photodissociation dynamics of diatomic anion

Abstract

A one-electron model for the photodissociation and recombination dynamics of a diatomic anion has been proposed. The main purpose of the study is to provide a simple model to better understand the effect of strong coupling between the solvent polarization and the extra charge in a system like I2−. The model diatomic anion consists of two identical nuclei and an extra electron whose dynamics are treated explicitly. The effect of solvent polarization is modeled by introducing an effective solvent field representing a nonequilibrium solvent configuration. Nonadiabatic theoretical calculations, in which the electronic and the nuclear dynamics are treated simultaneously, can reveal the importance of nonadiabatic effects by including intrinsically all the electronic states involved. It is found that a purely dissociative excited state can support recombination due to coupling of the anomalous charge distribution with the solvent polarization. The charge switching and the subsequent charge separation for the dissociating fragments are strongly coupled with the fluctuating solvent polarization, as represented by the time-dependent solvent field in the present model. The results of the calculations with varying time scales for the solvent response have demonstrated the possibility of numerous diverse phenomena resulting from nonadiabatic transitions. In particular, we found charge transfer induced by changing solvent polarization. The general model presented in the study provides a reasonable interpretation, at least on a qualitative level, for the interesting features obtained from recent experiments and nonadiabatic molecular dynamics studies on the photodissociation of I2− in molecular clusters.