Phase equilibria of polyaromatic hydrocarbons by hybrid Monte Carlo Wang–Landau simulations

Abstract

Using a combination of hybrid Monte Carlo simulations in the isothermal–isobaric ensemble with a Wang–Landau sampling, we parametrise a force field for polyaromatic hydrocarbons (PAHs). The proposed force field gives an accurate description of the vapour–liquid equilibria of naphthalene, phenanthrene and anthracene. In particular, the model yields a better account of the dependence of the vapour pressure on temperature than existing models. The strategy adopted in this work is markedly different from that followed in previous work, which relied on Gibbs Ensemble Monte Carlo (GEMC) simulations combined with configurational bias (CB) moves. The accuracy of the GEMC-CB method hinges on a reasonably high acceptance rate of the transfer of molecules from one phase to another, a condition difficult to achieve for large molecules like PAHs. Our approach avoids these transfers, allows for a direct determination of the coexistence data in the isothermal–isobaric ensemble and provides a promising alternative to the GEMC-CB approach.

Keywords:

• vapour–liquid equilibria
• hybrid Monte Carlo
• Wang–Landau sampling
• polyaromatic hydrocarbons

Acknowledgements

Financial support from ND EPSCoR through NSF grant EPS-0814442 is gratefully acknowledged. This material is based upon work supported under a National Science Foundation Graduate Research Fellowship (A.M.).