CAS-SCF and MM-VB Dynamics: Applications to Organic Photochemistry

The increased speed of modern computers makes trajectory computations where the gradient is evaluated on the fly a realistic possibility. For excited state processes one must deal with the non-adiabatic event where the trajectory passes from the excited state to the ground state. For this we have implemented (in CAS-SCF and in our MM-VB method) a surface hop type algorithm as well as a method where the trajectory propagates on a mixed state. Investigations have been performed for several problems relevant to photochemistry. The dynamics results show interesting chemical effects associated with tipped versus sloped conical intersections and effects associated with dynamically locked transient species.