Deterministic engines extending Helmholtz thermodynamics

Amilcare Porporato, Lamberto Rondoni

Research output: Contribution to journalArticlepeer-review


Helmholtz formalism provides a tantalizing interpretation of classical thermodynamics, based on time integrals of purely mechanical quantities and without need of statistical description. Here we extend this approach to include heat flux and pressure at the walls to enable it to describe actual thermodynamic transformations, such as isothermal compressions and expansions. The presence of hard walls, which gives rise to non zero pressure, is justified by means of the virial theorem, while the heat fluxes are introduced as quasi-static limits of suitably thermostatted Hamiltonians. Particular attention is paid to generalizing the minimalist cases of the harmonic oscillator and elastic bouncer, which afford clear physical interpretations. With such extensions, a complete picture of thermodynamics emerges, amenable to phase transitions and cyclic deterministic transformations, which produce mechanical work from heat, like the Carnot cycle.

Original languageEnglish (US)
Article number129700
JournalPhysica A: Statistical Mechanics and its Applications
StatePublished - Apr 15 2024
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Statistical and Nonlinear Physics
  • Statistics and Probability


  • Deterministic engines
  • Entropy
  • Helmholtz thermodynamics


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