We found that commonly used semiclassical nonadiabatic dynamics, namely trajectory surface hopping, semiclassical Ehrenfest, and coherent switching with decay of mixing (CSDM) fail to conserve nuclear angular momenta in direct dynamics. The failure is caused by the direct use of the space-frame (SF) for the nonadiabatic coupling vector (NAC) in standard electronic structure software. We showed how to eliminate the problem by using a projected NAC, in which translational and rotational parts are removed. The plots illustrate how projection reduces the problem by four orders of magnitude.
“Conservation of Angular Momentum in Direct Nonadiabatic Dynamics” Y. Shu, L. Zhang, Z. Varga, K. A. Parker, S. Kanchanakungwankul, S. Sun, and D. G. Truhlar, Journal of Physical Chemistry Letters 11, 1135 (2020). doi.org/10.1021/acs.jpclett.9b03749
