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Center for Nonlinear Studies |
When molecules are excited to an excited electronic state,non-adiabatic processes and couplings between different electronic states become important. Conical intersections (actual potential energy surface crossings) between two and three states of the same symmetry have been found to play a key role in these processes. Here we present studies where the importance of conical intersections is being investigated in photoinitiated processes of biologically relevant systems, and particularly the nucleobases and their analogs. Large scale ab initio multireference configuration interaction methods MRCI) are being used. Our results show the presence of many seams of two- or three-state conical intersections that can complicate the potential energy surfaces and dynamics of these systems. Solvent effects on excited states and conical intersections will also be discussed.