Combining rules

The combining rules (also known as mixing rules) for binary mixtures are variously given by

Berthelot rule

$\epsilon _{ij}={\sqrt {\epsilon _{ii}\epsilon _{jj}}}$

Lorentz rule

$\sigma _{ij}={\frac {\sigma _{ii}+\sigma _{jj}}{2}}$

See also Lennard-Jones model

Kong rules

(Ref. 2)

Waldman-Hagler rules

(Ref. 3)

Admur and Mason

For the second virial coefficient of a mixture (Ref. 4)

$B_{ij}={\frac {\left(B_{ii}^{1/3}+B_{jj}^{1/3}\right)^{3}}{8}}$

References

1. Jérôme Delhommelle; Philippe Millié "Inadequacy of the Lorentz-Berthelot combining rules for accurate predictions of equilibrium properties by molecular simulation", Molecular Physics 99 pp. 619-625 (2001)
2. Chang Lyoul Kong "Combining rules for intermolecular potential parameters. II. Rules for the Lennard-Jones (12–6) potential and the Morse potential", Journal of Chemical Physics 59 pp. 2464-2467 (1973)
3. M. Waldman and A. T. Hagler "New combining rules for rare-gas Van der-Waals parameters", Journal of Computational Chemistry 14 pp. 1077-1084 (1993)
4. I. Amdur and E. A. Mason "Properties of Gases at Very High Temperatures", Physics of Fluids 1 pp. 370-383 (1958)