Accelerated sampling by infinite swapping of path integral molecular dynamics with surface hopping
For researchers studying multi-level quantum systems, this work offers a method to significantly speed up thermal equilibrium sampling, though it is an incremental extension of existing path integral and surface hopping techniques.
The paper proposes an infinite swapping limit for a multi-level ring polymer representation to accelerate thermal equilibrium sampling in multi-level quantum systems, achieving huge improvements in sampling efficiency over direct path integral molecular dynamics with surface hopping.
To accelerate the thermal equilibrium sampling of multi-level quantum systems, the infinite swapping limit of a recently proposed multi-level ring polymer representation is investigated. In the infinite swapping limit, the ring polymer evolves according to an averaged Hamiltonian with respect to all possible surface index configurations of the ring polymer, thus connects the surface hopping approach to the mean-field path integral molecular dynamics. A multiscale integrator for the infinite swapping limit is also proposed to enable efficient sampling based on the limiting dynamics. Numerical results demonstrate the huge improvement of sampling efficiency of the infinite swapping compared with the direct simulation of path integral molecular dynamics with surface hopping.