Sensitivity of nonequilibrium relaxation to interaction potentials: Timescales of response from Boltzmann's H function

Kumar, S and Acharya, S and Bagchi, B (2023) Sensitivity of nonequilibrium relaxation to interaction potentials: Timescales of response from Boltzmann's H function. In: Physical Review E, 107 (2).

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Abstract

We investigate, by simulations and analytic theory, the sensitivity of nonequilibrium relaxation to interaction potential and dimensionality by using Boltzmann's H function H(t). We evaluate H(t) for three different intermolecular potentials in all three dimensions and find that the well-known H theorem is valid and that the H function exhibits rather strong sensitivity to all these factors. The relaxation of H(t) is long in one dimension, but short in three dimensions, longer for the Lennard-Jones potential than for the hard spheres. The origin of the ultraslow approach to the equilibrium of H(t) in one-dimensional systems is discussed. Importantly, we obtain a closed-form analytic expression for H(t) using the solution of the Fokker-Planck equation for velocity space probability distribution and compare its predictions with the simulation results. Interestingly, H(t) is found to exhibit a linear response when vastly different initial nonequilibrium conditions are employed. The microscopic origin of this linear response is discussed. The oft-quoted relation of H function with Clausius's entropy theorem is discussed. © 2023 American Physical Society.

Item Type:	Journal Article
Publication:	Physical Review E
Publisher:	American Physical Society
Additional Information:	The copyright for this article belongs to American Physical Society.
Keywords:	Fokker Planck equation; Probability distributions, Analytic theory; Boltzmann; H function; Interaction potentials; Intermolecular potentials; Linear response; Nonequilibrium relaxation; Simulation theory; Three dimensions; Timescale of response, Lennard-Jones potential
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	30 Mar 2023 06:07
Last Modified:	30 Mar 2023 06:07
URI:	https://eprints.iisc.ac.in/id/eprint/81170

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