Nonadiabatic molecular dynamics simulations are routinely used for the characterization of a variety of photoexcited chemical processes. The electronic state transition probability is conventionally obtained through analytic evaluation of the nonadiabatic coupling vector, however this approach may require a significant reduction in the time step of the simulation in order to ensure accuracy. Such time step reductions result in extra electronic structure calculations, making these simulations prohibitive for large systems. As a solution to this problem we present the norm-preserving interpolation (NPI) method, a scheme for accurate determination of electronic state transition probabilities through numerical evaluation of the time derivative coupling. This method is applicable in the case of arbitrary coupling strengths, does not require analytic calculation of the nonadiabatic coupling matrix elements, and is insensitive to the size of the dynamics time-step. This allows for highly accurate prediction of electronic state transition probabilities in wide-ranging chemical problems and with any suitable electronic structure method. We will discuss the performance of the NPI method, in comparison with analytic treatment of the nonadiabatic coupling vector, with application to chemical problems which present unique challenges for nonadiabatic molecular dynamics. In the case of dynamical long-range charge transfer, which results in trivially unavoided crossings between adiabatic electronic states, our analysis shows that the NPI method allows for the prediction of electronic state transition probabilities that are in error by only 0.1% under standard conditions.

Time-derivative coupling scheme for accurate electronic state transition probabilities in nonadiabatic molecular dynamics

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.