Assessment of the Effect of Mixing Rules on Predicting the Second Virial Coefficient and a Further Evidence of the Inadequacy of the Lorentz-Berthelot Rules

Ali K. Al-Matar, David A. Rockstraw


The Lorentz-Berthelot combining rules are the most commonly used in force fields estimation of cross terms for the collision diameter and well depth. In this work, a framework for assessing the effect of mixing rules on the second virial coefficients, or any other property of interest, is laid. Additionally, the effect of the mixing rules on the cross second virial coefficients of select binary gas systems is studied. Two new mixing rules in addition to the Lorentz-Berthelot, Halgren HHG, Waldman-Hagler and Tang-Toennies are implemented. The results provide a further evidence that the Lorentz-Berthelot rules are the least accurate among the rules studied. The new mixing rules (MADAR-1 and MADAR-2) and the Waldman-Hagler rules are the most appropriate to be used.


Mixing rules, MADAR Rules, Second Virial Coefficient, Collision Diameter, Well Depth

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