Evaluation of the importance of spin-orbit couplings in the nonadiabatic quantum dynamics with quantum fidelity and with its efficient 'on-the-fly' ab initio semiclassical approximation

摘要

We propose to measure the importance of spin-orbit couplings (SOCs) in thenonadiabatic molecular quantum dynamics rigorously with quantum fidelity. Tomake the criterion practical, quantum fidelity is estimated efficiently withthe multiple-surface dephasing representation (MSDR). The MSDR is asemiclassical method that includes nuclear quantum effects through interferenceof mixed quantum-classical trajectories without the need for the Hessian ofpotential energy surfaces. Two variants of the MSDR are studied, in which thenuclei are propagated either with the fewest-switches surface hopping or withthe locally mean field dynamics. The fidelity criterion and MSDR are firsttested on one-dimensional model systems amenable to numerically exact quantumdynamics. Then, the MSDR is combined with "on-the-fly" computed electronicstructure to measure the importance of SOCs and nonadiabatic couplings (NACs)in the photoisomerization dynamics of CH2NH2+ considering 20 electronic statesand in the collision of F + H2 considering six electronic states.