Second virial coefficients: a route to combining rules?

^†Dedicated to Johann Fischer on the occasion of his 75th birthday.

ABSTRACT

The effect of combining rules on the second virial coefficient is systematically examined for a series of n-alkanes up to octane with the aim to assess the impact of the individual site–site interactions and to find potential general regularities. To describe the interactions of n-alkanes, we use the TraPPE-UA force field and examine the effect of deviations from the Lorentz–Berthelot combining rule, both separately for the energy and length scaling parameters of the Lennard-Jones potential, and for their combined change. The results reveal the different impacts of both site–site interactions and distance and energy scaling parameters on the cross virial coefficient, which can potentially be used in force field development. An attempt is also made to find a scaling that could provide a uniform result.

KEYWORDS:

• Second virial coefficient
• n-alkane mixtures
• combining rules
• TraPPE force field
• site–site interactions
• Lorentz–Berthelot rule
• corresponding-state scaling

Acknowledgments

Support for this work was provided by the Czech Science Foundation (Project No. 15-19542S). We thank Andrew J. Schultz and David A. Kofke (NYSU at Buffalo) for indispensable help with using their Etomica framework.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Czech Science Foundation [Grant Number 15-19542S].