Excited state calculations have been performed to better understand the effects of optical processes, including light harvesting and intraband relaxations, on biological and synthetic systems. In particular, we are interested in situations where there are strong non-adiabatic effects driven by nuclear motion. Previously these calculations were limited to treating the entire system at the same level of theory, severely restricting the practical size of the systems of study. We apply a quantum mechanical method of excited state dynamics to a selected region of the system, while applying classical force field calculations to the rest, providing a hybrid excited state QM/MM MD simulation. The QM calculations provide support for adiabatic and non-adiabatic calculations using the Austin Model 1 (AM1) semi-empirical Hamiltonian, the Collective Electronic Oscillator (CEO) package for the excited state many body effects, and Tully’s fewest switches algorithm to determine the dynamics of the electronic structure. The implementation for the QM/MM excited state non-adiabatic molecular dynamics is done by interfacing with the program Amber. We apply this hybrid method to a variety of systems and compare the trajectory results to those calculated using the full QM method.

Non-adiabatic QM/MM: A hybrid approach to doing non-adiabatic excited state dynamics

253rd National Meeting (2017)

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