Lennard-Jones equation of state

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The equation of state of the Lennard-Jones model.

Johnson, Zollweg and Gubbins[edit]

Johnson, Zollweg and Gubbins [1] proposed an equation of state based on 33 parameters within a modified Benedict, Webb and Rubin equation of state, which accurately reproduces the vapour-liquid equilibrium curve.

Kolafa and Nezbeda[edit]

The Kolafa and Nezbeda equation of state [2] provides us with the Helmholtz energy function: (Eq. 30):

A=A_{\mathrm{HS}} + \exp (-\gamma \rho^2) \rho T \Delta B_{2,{\mathrm{hBH}}} + \sum_{ij} C_{ij} T^{i/2} \rho^j

the compressibility factor (Eq. 31)

z \equiv \frac{P}{\rho T}= z_{\mathrm{HS}} +  \rho(1-2\gamma\rho^2) \exp (-\gamma \rho^2) \Delta B_{2,{\mathrm{hBH}}} + \sum_{ij} jC_{ij} T^{i/2-1} \rho^j

and the internal energy (Eq. 32)

 {3(z_{\rm HS}-1)\over d_{\rm hBH}}\,
 {\partial d_{\rm hBH}\over \partial (1/T)}
 + \rho \exp(-\gamma\rho^2)\,{\partial \Delta B_{\rm2,hBH}\over\partial (1/T)}
 - \sum_{ij} \left({i\over2}-1\right) C_{ij}\, T^{i/2} \rho^j

On the following page is the FORTRAN code for the Kolafa and Nezbeda equation of state.


The Ree equation of state [3] is an extension of the earlier work of Hansen [4] in the high temperature region.

Boltachev and Baidakov[edit]

Boltachev and Baidakov have paid particular attention to including data from the metastable region [5].

Pieprzyk-Brańka-Maćkowiak and Heyes[edit]

The Pieprzyk-Brańka-Maćkowiak and Heyes equation of state [6] consists of a parameterisation of the modified Benedict, Webb and Rubin equation of state.


Related reading

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