Coupled-trajectory surface hopping with sign consistency

The framework of exact factorization (XF) has inspired a series of trajectory-based nonadiabatic dynamics methods by introducing different approximations. Recently, the coupled-trajectory surface hopping (CTSH) method has been proposed to combine the key advantages of the coupled-trajectory mixed quantum-classical method based on XF and the fewest switches surface hopping. We here present a novel variant of CTSH, namely, sign-consistent CTSH (SC-CTSH), which considers proper trajectory clustering to reconstruct the nuclear density distribution and the consistency between wave function and active states to introduce decoherence. Using the exact quantum solutions as references, the high performance of SC-CTSH is benchmarked in the widely studied scattering models and compared with other related XF-based methods. Due to the incorporation of new trajectory clustering and sign consistency algorithms, SC-CTSH obtains more accurate quantum momentum and decoherence during the nonadiabatic dynamics, which makes the combination of XF and surface hopping more consistent and reliable. This study further highlights the significance of internal consistency between wave function and active states, which is important in the further development of mixed quantum-classical dynamics methods.