We present the first implementation of multiconfiguration pair-density functional theory (MC-PDFT) ab initio molecular dynamics. MC-PDFT is a multireference electronic structure method that in many cases has a similar accuracy (or even better accuracy) the complete active space second-order perturbation theory (CASPT2) at a significantly lower computational cost. In this study, we introduced MC-PDFT analytical gradients into the SHARC molecular dynamics program for ab initio, nonadiabatic molecular dynamics simulations. We verify our implementation by examining the intersystem crossing dynamics of thioformaldehyde, and we observe excellent agreement with recent CASPT2 and experimental findings. Moreover, with MC-PDFT, we could perform dynamics simulations with the 12 electron in 10 orbitals active space that was computationally too expensive for direct dynamics with CASPT2.
Bibliographical noteFunding Information:
The authors are grateful to Matthew Hermes, Yinan Shu, Dihua Wu, and Chen Zhou for many helpful discussions of related topics. This work was supported by the National Science Foundation under grant CHE-2054723. The computational resources for this project were provided by the University of Chicago Research Computing Center (RCC).
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