Adiabatic wave-packet motion on conically intersecting potential energy surfaces. The case of SO 2( 1B 1 1A 2)

Abstract

3D wave-packet dynamical calculations have been performed for the coupled 1B 1 1A 2 electronics states of SO 2, based on large-scale CASSCF calculations of Rosmus and co-workers. The full anharmonic (diabatic) potential energy surfaces have been used while the vibronic coupling terms were taken to be a linear function of the asymmetric stretch coordinate. Due to dipole selection rules, the initial wave packet is created on the lower surface of the interacting states but above the minimum energy of their conical intersection. The calculations reveal that the wave packet remains confined basically to the initially populated adiabatic surface even after having approached and passed by the intersection seam. This interesting findings is put into perspective by comparing with other examples of wave-packet motion on conically intersecting surfaces. It helps to understand some basic features of the complex 1A 1→ 1B 1 absorption band system of SO 2.