Detail:

Abstract:
　　Modeling of non-equilibrium excited state processes in nanoscale systems create new challenges to time-domain density functional theory (TDDFT) and nonadiabatic molecular dynamics (NAMD). Examples include proper treatment of quantum coherence, transition from coherent to hopping transport in long-range charge and energy transfer, super-exchange, and many-particle Auger-type processes. Motivated by these challenges, our group developed several new NAMD techniques and implemented them within ab initio and tight-binding TDDFT. Decoherence-induced surface hopping (DISH) incorporates decoherence effects in a way that naturally achieves trajectory branching. Coherence penalty functional (CPF) uses DFT-like ideas to introduce decoherence into the Ehrenfest method. Self-consistent fewest-switches surface hopping (SC-FSSH) provides a simple solution to the trivial (or “unavoided”) crossings in FSSH. Global flux surface hopping (GFSH) generalizes FSSH to treat super-exchange. Second quantized surface hopping (SQUASH) utilizes second quantization and generalizes FSSH to include both super-exchange and decoherence effects. Extended from Hilbert to Liouville space, FSSH and GFSH improve treatment of coherence and Auger-type processes. The key ideas underlying these NAMD-TDDFT approaches will be introduced and illustrated by applications to excited state dynamics in nanoscale materials.