Combining rules

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

Admur and Mason

For the second virial coefficient of a mixture

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

Fender-Halsey

The Fender-Halsey combining rule for the Lennard-Jones model is given by

$\epsilon _{ij}={\frac {2\epsilon _{i}\epsilon _{j}}{\epsilon _{i}+\epsilon _{j}}}$

Gilbert-Smith

The Gilbert-Smith rules for the Born-Huggins-Meyer potential.

Good-Hope rule

The Good-Hope rule for Mie–Lennard‐Jones or Buckingham potentials is given by (Eq. 2):

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

Lorentz-Berthelot rules

The Lorentz rule is given by .

References

Related reading

• Thomas A. Halgren "The representation of van der Waals (vdW) interactions in molecular mechanics force fields: potential form, combination rules, and vdW parameters", Journal of the American Chemical Society 114 pp. 7827-7843 (1992)