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
We propose to measure the importance of spin-orbit couplings (SOCs) in the nonadiabatic molecular quantum dynamics rigorously with quantum ﬁdelity. To make the criterion practical, quantum ﬁdelity is estimated efﬁciently with the multiple-surface dephasing representation (MSDR). The MSDR is a semiclassical method that includes nuclear quantum effects through interference of mixed quantumclassical trajectories without the need for the Hessian of potential energy surfaces. Two variants of the MSDR are studied, in which the nuclei are propagated either with the fewest-switches surface hopping or with the locally mean ﬁeld dynamics. The ﬁdelity criterion and MSDR are ﬁrst tested on one-dimensional model systems amenable to numerically exact quantum dynamics. Then, the MSDR is combined with “on-the-ﬂy” computed electronic structure to measure the importance of SOCs and nonadiabatic couplings in the photoisomerization dynamics of CH2NH 2 considering 20 electronic states and in the collision of F + H2 considering six electronic states.
Record created on 2012-08-10, modified on 2016-08-09