Quantum photochemistry: Coupled surfaces and coupled dynamics

This thesis presents the results of quantum mechanical dynamics calculations and semiclassical trajectory calculations on a variety of electronically nonadiabatic chemical processes. Chapter 1 presents an introduction to the thesis. Chapter 2 presents multi-state electronic structure calculations on the NaH2 system and an analytical potential energy matrix designed to fit these electronic structure calculations. Chapter 3 presents accurate quantum mechanical dynamics calculations on the predissociation of the A state of NaH2 using the newly developed NaH2 potential matrix. These quantum mechanical calculations are used as a standard against which approximate semiclassical methods are tested. Chapter 4 compares semiclassical trajectory calculations against accurate quantum mechanical calculations for two different potential matrices describing the NaH2 system. Differences between accurate and approximate methods for each potential matrix are discussed, as are the effects that the differences between the two potential matrices have on the resulting dynamics. We show that these differences lead to new criteria for picking the best representation in which to perform trajectory surface hopping calculations. Chapter 5 summarizes the work in testing and developing semiclassical methods.