posted on 2020-01-27, 22:29authored byYinan Shu, Linyao Zhang, Zoltán Varga, Kelsey A. Parker, Siriluk Kanchanakungwankul, Shaozeng Sun, Donald G. Truhlar
Direct
nonadiabatic dynamics is used to study processes involving
multiple electronic states from small molecules to materials. Compared
with dynamics with fitted analytical potential energy surfaces, direct
dynamics is more user-friendly in that it obtains all needed energies,
gradients, and nonadiabatic couplings (NACs) by electronic structure
calculations. However, the NAC that is usually used does not conserve
angular momentum or the center of mass in widely used mixed quantum-classical
nonadiabatic dynamics algorithms, in particular, trajectory surface
hopping, semiclassical Ehrenfest, and coherent switching with decay
of mixing. We show that by using a projection operator to remove the
translational and rotational components of the originally computed
NAC, one can restore the conservation.