Multiconfiguration pair-density functional theory (MC-PDFT) is a multireference electronic structure method that in many cases has a similar accuracy (or even better accuracy) than complete active space second order perturbation theory (CASPT2) at a significantly lower computational cost. MC-PDFT analytical gradients have been developed recently, and they may be used to apply MC-PDFT to dynamical simulations of strongly correlated systems. In this presentation, I will present the first implementation of MC-PDFT ab initio molecular dynamics. This involves the introduction of MC-PDFT analytical gradients into the SHARC molecular dynamics program for ab initio, nonadiabatic molecular dynamics simulations. I will show work that verifies our implementation by examining the intersystem crossing dynamics of thioformaldehyde, and show that we observe excellent agreement with recent CASPT2 and experimental findings, while simulating MC-PDFT with an active space that was computationally too expensive for CASPT2.

Nonadiabatic molecular dynamics by multiconfiguration pair-density functional theory

ACS Spring 2022

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