<title>Theory and simulation of condensed-phase ultrafast dynamics</title>

Abstract

In this paper, we describe a new approach to simulating many-body molecular dynamics on coupled electronic surfaces. The method is based on a semiclassical limit of the quantum Louisville equation, which yields equations of motion for classical-like distribution functions describing both nuclear probability densities on the coupled surfaces and the coherences between the electronic states. The Hamiltonian dynamics underlying the evolution of these distributions is augmented by nonclassical source and sink terms, which allow the flow of probability between the coupled surfaces and the corresponding formation and decay of electronic coherences. We show that this approach reproduces the familiar Landau-Zehnder transition probability in the limit of weak electronic coupling. In addition, we describe a trajectory-based implementation in the context of a conventional molecular dynamics simulation.