Towards the Realization of Ab Initio Dynamics at the Speed of Molecular Mechanics: Simulations with Interpolated Diabatic Hamiltonian

Abstract

Understanding photochemical processes often requires accurate descriptions of the nonadiabatic events involved. The cost of accurate quantum chemical simulations of the nonadiabatic dynamics of complex systems is typically high. Here, we discuss the use of interpolated quasi-diabatic potential-energy matrices, which aims to reduce the computational cost with minimal sacrifices in accuracy. It is shown that interpolation reproduces the reference ab initio information satisfactorily for a sizeable chromophore in terms of its adiabatic energies and derivative coupling vectors. Actual nonadiabatic simulation results of the chromophore in the gas phase and in aqueous solution are presented, and it is demonstrated that the interpolated quasi-diabatic Hamiltonian can be applied to studying nonadiabatic events of a complex system in an ensemble manner at a much-reduced cost. Limitations, and how they can be overcome in future studies, are also discussed.