QuantumClassical Modeling of Chemical Phenomena
CSIC Building (#406),
Seminar Room 4122.
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Very accurate surface hopping calculations
Michael Herman
Tulane University

Abstract:
Many problems in chemistry involve processes in which atoms or molecules undergo transitions between electronic quantum states. A semiclassical surface hopping expansion of the multistate wave function and propagator is discussed. The surface hopping expansion is capable of obtaining very accurate results even for cases in which interference between significantly different paths plays an important role. It is shown that hops in the classically forbidden region must be included at low energies to maintain the high level of accuracy. High accuracy is obtained even in cases where the transition probability is very small because the transition is strongly classically forbidden. A relatively simple one dimensional approximation, which uses only information obtained near the classical turning point in the motion, is also shown to provide accurate results for these forbidden transitions. A form of the surface hopping expansion, which is free of semiclassical singularities, will also be discussed. 
