Simulation of nonadiabatic wave packet interferometry using classical trajectories

In this paper, we describe the application of our recently developed multis tate semiclassical Liouville equation method for modeling molecular dynamic s on multiple coupled electronic states [C. C. Martens and J.-Y. Fang, J. C hem. Phys. 106, 4918 (1997); A. Donoso and C. C. Martens, J. Phys. Chem. 10 2, 4291 (1998)] to problems where electronic coherence effects play a domin ant role. We consider a model problem involving the simultaneous evolution of wave packets on two coupled electronic states. We analyze the problem qu alitatively from both quantum and semiclassical perspectives using perturba tion theory, and identify the roles played by coupling strength and relativ e phase of the initial wave packets. We then perform trajectory-based simul ations on a two-state one-dimensional model problem and compare the results with those of exact quantum calculations. In marked contrast with most cur rent methods for modeling nonadiabatic dynamics with classical trajectories , the semiclassical Liouville method is found to be capable of treating eve n dominant electronic coherence effects in a consistent and accurate manner . (C) 2000 American Institute of Physics. [S0021-9606(00)01417-3].