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Comparison of Matsubara dynamics with exact quantum dynamics for an oscillator coupled to a dissipative bath.

Accepted version
Peer-reviewed

Type

Article

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Authors

Pós, Eszter S 

Abstract

We report the first numerical calculations in which converged Matsubara dynamics is compared directly with exact quantum dynamics with no artificial damping of the time-correlation functions (TCFs). The system treated is a Morse oscillator coupled to a harmonic bath. We show that, when the system-bath coupling is sufficiently strong, the Matsubara calculations can be converged by explicitly including up to M = 200 Matsubara modes, with the remaining modes included as a harmonic "tail" correction. The resulting Matsubara TCFs are in near-perfect agreement with the exact quantum TCFs, for non-linear as well as linear operators, at a temperature at which the TCFs are dominated by quantum thermal fluctuations. These results provide compelling evidence that incoherent classical dynamics can arise in the condensed phase at temperatures at which the statistics are dominated by quantum (Boltzmann) effects, as a result of smoothing of imaginary-time Feynman paths. The techniques developed here may also lead to efficient methods for benchmarking system-bath dynamics in the overdamped regime.

Description

Keywords

5108 Quantum Physics, 34 Chemical Sciences, 3406 Physical Chemistry, 51 Physical Sciences, 5102 Atomic, Molecular and Optical Physics

Journal Title

J Chem Phys

Conference Name

Journal ISSN

0021-9606
1089-7690

Volume Title

Publisher

AIP Publishing