Equilibration

This article describes equilibration in terms of thermodynamic systems, for equilibration in terms of numerical mathematics, see equilibration

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As equilibration (or equilibration ) is the process in which a system in its equilibrium state transitions. The equilibration process does not need to be driven externally, but runs (in closed and undisturbed systems) by itself in a non-equilibrium process .

The term equilibration is used in particular in thermodynamics and statistical physics to describe that a physical system passes through equilibration into its thermodynamic state of equilibrium, i.e. thermalized . The time it takes for this to happen is called the equilibration time. It plays an important role in numerical simulations of physical systems such as Monte Carlo simulations , since the measured variables only reflect the desired state of equilibrium of the system after a sufficiently long equilibration time has elapsed. The time it takes a system to equilibrate depends heavily on the system and the temperature , and is therefore often not easy to determine.

Theoretical descriptions

The process of equilibration can be described with the help of the H-theorem or generalizations of it (such as the relaxation theorem ): A closed system always develops (on average) towards the state of maximum entropy, i.e. during the process of equilibration, entropy is produced . How a system reacts to external disturbances of the equilibrium is described by transport coefficients (see also Onsager's reciprocity relations ).

Individual evidence

1. ↑ David P. Landau , Kurt Binder : A Guide to Monte Carlo Simulations in Statistical Physics (Cambridge University Press, 2014, 4th ed.), P. 160, ISBN 978-1107074026
2. ↑ James C. Reid, Denis J. Evans, Debra J. Searles: Communication: Beyond Boltzmann's H-theorem: Demonstration of the relaxation theorem for a non-monotonic approach to equilibrium . In: The Journal of Chemical Physics . tape 136 , no. 2 , January 11, 2012, ISSN  0021-9606 , p. 021101 , doi : 10.1063 / 1.3675847 ( scitation.org [accessed June 25, 2019]).