Quantum hydrodynamics: Mixed states, dissipation, and a new hybrid quantum-classical approach

The formulation of quantum hydrodynamics for mixed states provides a complement, in a quantum-statistical context, to its pure-state Bohmian mechanics analogue. We summarize our recent work in this area, focusing on two key aspects. We first describe the formulation of a generalized hydrodynamic force, which includes the effects of thermal fluctuations and quantum fluctuations and thus determines the time evolution under the influence of dissipation. Second, we introduce a mixed hydrodynamic-Liouville space representation in terms of partial moments, as applied in the context of coupled electronic states and mixed quantum-classical dynamics. (C) 2004 Wiley Periodicals, Inc.