Assessing the performance of coupled-trajectory schemes on full-dimensional two-state linear vibronic coupling models

We investigate the performance of coupled-trajectory methods for nonadiabatic molecular dynamics in simu- lating the photodynamics of 4-(dimethylamino)benzonitrile (DMABN) and fulvene, with electronic structure provided by linear vibrational coupling models. We focus on the coupled-trajectory mixed quantum-classical (CTMQC) algorithm and on the (combined) coupled-trajectory Tully surface hopping (C)CTTSH in com- parison to independent-trajectory approaches, such as multi-trajectory Ehrenfest and Tully surface hopping. Our analysis includes not only electronic populations but also additional electronic and nuclear properties in position and momentum space. For both DMABN and fulvene, the recently-developed CCTTSH algorithm successfully resolves the internal inconsistencies of CTTSH. Instead, we find that DMABN highlights a sig- nificant weakness of CTMQC, which arises when the trajectories remain for long time in the vicinity of a region of strong nonadiabaticity.