Classical motion of the charge asymmetry in slow atomic collisions. I. Single-electron motion derived from Ehrenfest's theorem

The time evolution of the quantum mechanical mean value for the charge asymmetry (or the longitudinal dipole moment) of a diatomic collision system is described by classical equations of motion. These equations are derived from a modified Ehrenfest's theorem for a single-electron system. Trajectories as a function of the internuclear separation and the charge asymmetry are calculated for the collision system p+H. The electron transfer probability computed by sampling over trajectories with different initial conditions in its impact parameter dependence reflects the charge oscillations in the reaction zone.