Choosing a Model and Appropriate Transition Dipole Moments for Time-Dependent Calculations of Intervalence Electronic Transitions

Abstract

Intervalence electron transfer spectra in mixed-valence molecules are frequently modeled by an interacting pair of adiabatic potential energy surfaces. The presence or absence of a double minimum in the lower surface is correlated with trapped or delocalized charges, respectively. In the time-dependent picture of the spectroscopy, calculations are conveniently carried out in a diabatic basis. The choice of a diabatic basis for a given adiabatic potential surface is not unique. The appropriateness of a given representation depends on the physical model that is chosen to represent the system. We present three diabatic models that give the same adiabatic potential surface. The first model represents charge transfer between two sites, the second represents a transition between bonding and antibonding molecular orbitals, and the third represents a nonbonding to nonbonding transition. Each of these models gives rise to a different calculated absorption spectrum even though they arise from the same adiabatic pic...