The phase space CCS approach to quantum and semiclassical molecular dynamics for high-dimensional systems

The paper reviews the new coupled coherent states (CCS) technique for solution of the time-dependent Schrodinger equation in phase space, as a method for simulating the quantum dynamics of high-dimensional systems. The method is fully quantum although it exploits grids of CS guided by classical mechanics. As distinct from other trajectory guided approaches, the trajectories that carry the coherent states are governed by the classical equivalent of a quantum mechanically ordered Hamiltonian, that ensures optimal cancellation in quantum mechanical coupling terms. The resulting smoothness in the kernel of the integro-differential equation is therefore well adapted for Monte Carlo sampling. The simplest non-unitary version of the theory also obviates the need to invert large overlap matrices. Unitary corrections are also included and the analytical connection with uncoupled semiclassical initial value representation (IVR) techniques is described in detail. A variety of applications are presented. (C) 2004 Elsevier B.V. All rights reserved.