Fewest switch surface hopping method

Surface Hopping Model (SHM) first proposed by Tully and Preston [444] is a practical method to cope with nonadiabatic transition. It is actually not a theory but an intuitive prescription to take account of quantum coherent jump by replacing with a classical hop from one potential energy surface to another with a transition probability that is borrowed from other theories of semiclassical (or full quantum mechanical) nonadiabatic transitions state theory such as Zhu-Nakamura method. The fewest switch surface hopping method [445] and the theory of natural decay of mixing [197, 452, 509, 515] are among the most advanced methodologies so far proposed to practically resolve the critical difficulty of SET and the primitive version of SHM. 

Tully s fewest switch surface hopping method and its variants... 

How well the PSANB method works with such densely quasi-degenerate nonadiabatic systems was assessed. Prom the practical aspect, the PSANB scheme in fact reduces the number of initial points needed for qualitatively (but not quantitatively) converged result compared to the fewest switches surface hopping (FSSH) method, one of the most reliable and flexible methods to date. [496] This feature is preferable for tracing branches of electron wavepackets. 

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