A mean-field algorithm with decoherence and detailed balance for nonadiabatic molecular dynamics

Decoherence and detailed balance are two major issues for mixed quantum/classic nonadiabatic molecular dynamics (NAMD) simulations. In this work we introduce a new mean-field dynamics approach with decoherence and detailed balance (MF-DD) for NAMD. This method is able to explicitly treat the decoherence between different pairs of electronic states. Moreover, the energy-increasing and energy-decreasing electronic transitions are distinguished by dividing the density matrix into two parts. The detailed balance correction is then included by a Boltzmann factor applied to the energy-increasing transitions. The MF-DD is applied to study hot-hole cooling and transfer processes in Si quantum dot (QD) systems. The calculated hot carrier relaxation time is in consistent with experiments. In the QD-pair systems, the cooling time shows weak dependence with the QD spacing. However, the charge transfer rate between QDs is found to decreases exponentially as the QD spacing increases, which is attributed to the decreased state anticrossing strength. When the QD spacing is smaller than 1.1 nm, the hot-carrier transfer between two QDs can be quite efficient. It is also shown that the explicit treatment of decoherence time is important.