Multiple pathways in the photodynamics of a polar π-bond: A case study of silaethylene

Surface-hopping dynamics carried out on-the-fly was performed by means of quantum chemical multireference configuration interaction methods in order to investigate the photodynamics of silaethylene (SiCH4). The evolution of the S0 and S1 states were investigated during the first 100 fs after photoexcitation. In contrast to expectations based on previous static calculations, two mechanisms were found, corresponding to two minimum energy paths, which show characteristically different lifetimes. The bipyramidalization vs. torsion and stretching modes were identified to be responsible for this behavior driving the molecule into one of the two pathways.