Monte Carlo approach to the decay rate of a metastable system with an arbitrarily shaped barrier.
A path integral Monte Carlo method based on the fast-Fourier transform technique combined with the important sampling method is proposed to calculate the decay rate of a metastable quantum system with an arbitrary shape of a potential barrier. The contribution of all fluctuation actions is included which can be used to check the accuracy of the usual steepest-descent approximation, namely, the perturbation expansion of potential. The analytical approximation is found to produce the decay rate of a particle in a cubic potential being about 20% larger than the Monte Carlo data at the crossover temperature. This disagreement increases with increasing complexity of the potential shape. We also demonstrate via Langevin simulation that the postsaddle potential influences strongly upon the classical escape rate.
Bao
Jing-Dong
JD
Department of Physics, Beijing Normal University, Beijing 100875, China. jdbao@bnu.edu.cn
Bi
Lei
L
Jia
Ying
Y
D002627:Chemistry, Physical / Q000379:methods*; D015233:Models, Statistical; D008962:Models, Theoretical; D009010:Monte Carlo Method; D016011:Normal Distribution; D011789:Quantum Theory; D012984:Software; D013696:Temperature