A probabilistic approach to system-environment coupling

Fuente: arXiv
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Auteurs principaux: Rahbar, Mohammad, Stein, Christopher J.
Format: Preprint
Publié: 2025
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author Rahbar, Mohammad
Stein, Christopher J.
author_facet Rahbar, Mohammad
Stein, Christopher J.
contents We introduce a unified statistical framework for quantifying system-environment coupling by treating the interaction energy $V_\mathcal{SE}$ as a stochastic variable. Using a reference-particle decomposition, we derive exact, closed-form expressions for the mean and variance of $V_\mathcal{SE}$ in terms of the single-particle density and up to four-body correlation functions. When $V_\mathcal{SE}$ is approximately Gaussian, these two moments suffice to compute the free energy shift of the strongly coupled system. To validate our framework, we ran explicit Monte Carlo simulations of the full system-environment configurations across a range of system sizes, generating reference distributions of the interaction energy $V_\mathcal{SE}$. We then applied our derived analytical formulas to predict these distributions and found excellent agreement in both the weak- and strong-coupling regimes.
format Preprint
id arxiv_https___arxiv_org_abs_2505_00192
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A probabilistic approach to system-environment coupling
Rahbar, Mohammad
Stein, Christopher J.
Chemical Physics
Statistical Mechanics
We introduce a unified statistical framework for quantifying system-environment coupling by treating the interaction energy $V_\mathcal{SE}$ as a stochastic variable. Using a reference-particle decomposition, we derive exact, closed-form expressions for the mean and variance of $V_\mathcal{SE}$ in terms of the single-particle density and up to four-body correlation functions. When $V_\mathcal{SE}$ is approximately Gaussian, these two moments suffice to compute the free energy shift of the strongly coupled system. To validate our framework, we ran explicit Monte Carlo simulations of the full system-environment configurations across a range of system sizes, generating reference distributions of the interaction energy $V_\mathcal{SE}$. We then applied our derived analytical formulas to predict these distributions and found excellent agreement in both the weak- and strong-coupling regimes.
title A probabilistic approach to system-environment coupling
topic Chemical Physics
Statistical Mechanics
url https://arxiv.org/abs/2505.00192