Negative specific heats: where Clausius and Boltzmann entropies separate

Fuente: arXiv
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Autores principales: Bogers, Lander, Khodabandehlou, Faezeh, Maes, Christian
Formato: Preprint
Publicado: 2025
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author Bogers, Lander
Khodabandehlou, Faezeh
Maes, Christian
author_facet Bogers, Lander
Khodabandehlou, Faezeh
Maes, Christian
contents Steady nonequilibria dissipate energy and, when changing external parameters, an extra or excess heat accompanies the relaxation to the new nonequilibrium condition. For nonequilibrium systems in contact with a thermal bath, the heat capacity is defined as that excess heat per degree temperature for a quasistatic change of the bath temperature. It is fairly common to find negative heat capacities for steady nonequilibrium systems, in contrast with the situation for systems in thermal equilibrium. We discuss and illustrate the origin of that negative thermal response using Markov models. We find that the negativity results from an anticorrelation between quasipotential and (a change in) pseudopotential, the first measuring (excess) heat (and Clausius entropy), and the latter being related to the Boltzmann entropy. It can be quantified via an appropriate choice of effective temperatures.
format Preprint
id arxiv_https___arxiv_org_abs_2503_15999
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Negative specific heats: where Clausius and Boltzmann entropies separate
Bogers, Lander
Khodabandehlou, Faezeh
Maes, Christian
Statistical Mechanics
Soft Condensed Matter
Steady nonequilibria dissipate energy and, when changing external parameters, an extra or excess heat accompanies the relaxation to the new nonequilibrium condition. For nonequilibrium systems in contact with a thermal bath, the heat capacity is defined as that excess heat per degree temperature for a quasistatic change of the bath temperature. It is fairly common to find negative heat capacities for steady nonequilibrium systems, in contrast with the situation for systems in thermal equilibrium. We discuss and illustrate the origin of that negative thermal response using Markov models. We find that the negativity results from an anticorrelation between quasipotential and (a change in) pseudopotential, the first measuring (excess) heat (and Clausius entropy), and the latter being related to the Boltzmann entropy. It can be quantified via an appropriate choice of effective temperatures.
title Negative specific heats: where Clausius and Boltzmann entropies separate
topic Statistical Mechanics
Soft Condensed Matter
url https://arxiv.org/abs/2503.15999