Quantum Molecular Dynamics

Electron or ion dynamics are treated using spin-dependent quantum trajectories. These trajectories are inferred from the Dirac current, which contributes Schroedinger's current and additional spin-dependent terms, all of which are of order c(0) in the nonrelativistic regime of particle velocity, where c is the speed of light. The many-body problem is treated precisely as in classical dynamics. Each electron or ion has its own equation of motion, which is the time-dependent Dirac or the time-dependent Schroedinger equation in the relativistic or nonrelativistic regime of particle velocity, respectively. As an example the theory is applied to the electronic structure of the helium atom, in which two electrons with opposite spin states are shown to correlate such that their quantum trajectories keep them on average on opposite sides of the nucleus. As the theory is time dependent, excited states are also generated. (C) 2009 Wiley Periodicals, Inc. Int J Quantum Chem 111: 1-7, 2011