Editing Test volume method
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An alternative to the [[virial pressure]] route to calculating the pressure, there is a method which consists on | |||
evaluating the change in [[internal energy]], <math>\Delta U</math> produced by a small change in the volume of the system | evaluating the change in [[internal energy]], <math>\Delta U</math> produced by a small change in the volume of the system <math>\Delta V</math>. It can be shown that | ||
:<math> p = \frac{ k_B T N}{V} + \frac{ k_B T }{ \Delta V } \log \langle \exp(-\Delta U/k_B T )\rangle,</math> | :<math> p = \frac{ k_B T N}{V} + \frac{ k_B T }{ \Delta V } \log \langle \exp(-\Delta U/k_B T )\rangle,</math> | ||
where <math>k_B</math> is the [[Boltzmann constant]] and <math>T</math> is the [[temperature]]. | where <math>k_B</math> is the [[Boltzmann constant]] and <math>T</math> is the [[temperature]]. | ||
The method is clearly inspired by the [[ Widom test-particle method]] | |||
The method is clearly inspired by the [[ Widom test-particle method]] to obtain the [[chemical potential]]. | |||
==References== | ==References== | ||
#[http://dx.doi.org/10.1063/1.472721 V. I. Harismiadis, J. Vorholz, and A. Z. Panagiotopoulos "Efficient pressure estimation in molecular simulations without evaluating the virial", Journal of Chemical Physics '''105''' | #[http://dx.doi.org/10.1063/1.472721 V. I. Harismiadis, J. Vorholz, and A. Z. Panagiotopoulos "Efficient pressure estimation in molecular simulations without evaluating the virial", Journal of Chemical Physics '''105''' p. 8469 ] | ||