Decoherence in First-Principles Simulation of Excited Electron Dynamics in Nanomaterials and at Interfaces

Understanding hot carrier dynamics in nanomaterials and at molecule-material interfaces is central to gain scientific insights into the operation of various future optoelectronic technologies. We investigate the excited electron dynamics at molecule-material interfaces using first-principles simulation based on the fewest switches surface hopping (FSSH) method. Within the FSSH method, identification of trivial crossings poses a major numerical challenge in practice as it can influence simulation results in a few different ways. In particular, calculation of the decoherence rate from the energy autocorrelation function is found to be rather sensitive to the trivial crossings. In addition to discussing how decoherence influences both hot electron relaxation and transfer at interfaces, we propose a numerical method to treat trivial crossings and discuss the extent to which trivial crossings affect the calculated decoherence rate.