The quantum trajectory-guided adaptive Gaussian methodology in the Libra software package

In this paper, we report an implementation of the quantum trajectory-guided adaptive Gaussian (QTAG) method in a modular open-source Libra package for quantum dynamics calculations. The QTAG method is based on a representation of wavefunctions in terms of a quantum trajectory-guided adaptable Gaussians basis and is generalized for time-propagation on multiple coupled surfaces to be applicable to model nonadiabatic dynamics. The potential matrix elements are evaluated within either the local harmonic or bra-ket-average (linear) approximations to the potential energy surfaces, the latter being a more practical option. Performance of the QTAG method is demonstrated and discussed for the Holstein and Tully models, which are the standard benchmarks for method development in the area of nonadiabatic dynamics.