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.
Bibliographical noteFunding Information:
This work was partially supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under award DE-SC0015997, by the National Natural Science Foundation of China (grant no. 51536002), and by the Air Force Office of Scientific Research under grant no. FA9550-19-1-0219.
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