Time-dependent many-electron approach to slow ion-atom collisions for systems with several active electrons

We develop a first-principles molecular dynamics for slow ion-atom collisions, where a many-electron system is described over time allowing for its self-consistent coupling to evolving nuclear motions. Our treatment combines an eikonal description of nuclear motions and time-dependent Hartree-Fock states and introduces molecular orbitals written as linear combinations of traveling atomic functions to derive general matrix equations for state-to-state cross sections and to calculate properties. A “relax-and-drive” procedure is employed to propagate solutions to the coupled equations with different time scales for electronic transitions and nuclear displacements. Reduced differential cross sections have been calculated for elastic, electron transfer, and excitation processes in He⁺+D collisions, and they compare very well to experimental values and other calculations. In addition, we present results for the evolution of atomic populations during collisions.