Time-Dependent Multi-Component Density Functional Theory for Coupled Electron-Positron-Nuclear Dynamics

Positrons have been studied and utilized in various fields of molecular physics and surface science. We are particularly interested in dynamics of positron-atom compound systems under laser fields, which has been actively conducted mainly by experiments, because the microscopic mechanism of correlated dynamics of positrons with electrons and nuclei in these experiments is far from understanding. Here we propose and develop time-dependent multi-component density functional theory (TDMCDFT) for coupled electron-positron dynamics to explore the dynamics of positron-molecular compound systems. This TDMCDFT is a first-principles approach that can simulate formally exact excited state quantum dynamics of coupled electron-positron systems. In the present work we propose an adiabatic local density approximation for time-dependent electron-positron correlation. We apply this TDMCDFT approach to the dynamics of positron detachment from polar and non-polar molecules under various laser fields. Furthermore we derive the TDMCDFT-Ehrenfest molecular dynamics scheme to account for the coupling to nuclear motion. We elucidate the difference in the dynamics between polar and non-polar molecules and how laser intensity and frequency and nuclear motion play a role for efficient positron detachment.