Minimum-exponents ansatz for molecular dynamics and quantum dissipation

Jin-Jin Ding; Hou-Dao Zhang; Yao Wang; Rui-Xue Xu; Xiao Zheng; YiJing Yan

doi:10.1063/1.4967964

Minimum-exponents ansatz for molecular dynamics and quantum dissipation

J Chem Phys. 2016 Nov 28;145(20):204110. doi: 10.1063/1.4967964.

Authors

Jin-Jin Ding¹, Hou-Dao Zhang², Yao Wang², Rui-Xue Xu², Xiao Zheng², YiJing Yan²

Affiliations

¹ School of Chemistry and Chemical Engineering, Nantong University, Nantong, Jiangsu 226019, China.
² Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics and iChEM and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.

PMID: 27908096
DOI: 10.1063/1.4967964

Abstract

A unified theory for minimum exponential-term ansatzes on bath correlation functions is proposed for numerically efficient and physically insightful treatments of non-Markovian environment influence on quantum systems. For a general Brownian oscillator bath of frequency Ω and friction ζ, the minimum ansatz results in the correlation function a bi-exponential form, with the effective Ω¯ and friction ζ¯ being temperature dependent and satisfying Ω¯/Ω=(ζ¯/ζ)^1/2=r¯_BO/r_BO≤ 1, where r¯_BO=ζ¯/(2Ω¯) and r_BO=ζ/(2Ω). The maximum value of r¯_BO=r_BO can effectively be reached when k_BT≥ 0.8Ω. The bi-exponential correlation function can further reduce to single-exponential form, in both the diffusion (r_BO≫1) limit and the pre-diffusion region that could occur when r_BO≥ 2. These are remarkable results that could be tested experimentally. Moreover, the impact of the present work on the efficient and accuracy controllable evaluation of non-Markovian quantum dissipation dynamics is also demonstrated.