Non-adiabatic quantum molecular dynamics: ionization of many-electron systems

Abstract

We propose a novel method to describe realistically ionization processes with\nabsorbing boundary conditions in basis expansion within the formalism of the\nso-called Non-Adiabatic Quantum Molecular Dynamics. This theory couples\nself-consistently a classical description of the nuclei with a quantum\nmechanical treatment of the electrons in atomic many-body systems. In this\npaper we extend the formalism by introducing absorbing boundary conditions via\nan imaginary potential. It is shown how this potential can be constructed in\ntime-dependent density functional theory in basis expansion. The approach is\nfirst tested on the hydrogen atom and the pre-aligned hydrogen molecular ion\nH2+ in intense laser fields where reference calculations are available. It is\nthen applied to study the ionization of non-aligned H2+ and H2. Striking\ndifferences in the orientation dependence between both molecules are found.\nSurprisingly, enhanced ionization is predicted for perpendicularly aligned\nmolecules.\n