Simulation of ultrafast photodynamics of pyrrole with a multiconfigurational Ehrenfest method

Abstract

We report the first results of ab initio multiconfigurational Ehrenfest simulations of pyrrole photodynamics. We note that, in addition to the two intersections of 1¹A₂ and 1¹B₁ states with the ground state 1¹A₁, which are known to be responsible for N–H bond fission, another intersection between the 1²A₂ and 1²B₁ states of the resulting molecular radical becomes important after the departure of the H atom. This intersection, which is effectively between the two lowest electronic states of the pyrrolyl radical, may play a significant role in explaining the branching ratio between the two states observed experimentally. The exchange of population between the two states of pyrrolyl occurs on a longer scale than that of N–H bond fission.