Monte Carlo Simulations of the Liquid-Vapor Interface of Lennard-Jones Diatomics for the Direct Determination of the Interfacial Tension Using the Test-Area Method

摘要

We have performed Monte Carlo simulations to examine the vapor-liquid interface of systems of homonuclear diatomic Lennard-Jones (LJ) molecules. The test-area (TA) method developed by Gloor et al. (J. Chem. Phys., 2005, 123, 134703) is used to determine the vapor-liquid interfacial tension; the coexistence properties, such as densities and vapor pressures, are also reported. The TA method involves a thermodynamic (free energy perturbation) route to the tension which from a computational point of view offers some advantages over the more common mechanical (virial) route of Kirkwood and Buff (J. Chem. Phys. 1949, 17, 338). Simulation data are reported for LJ diatomics with different bond lengths L* = L/σ = 0.3292, 0.505,0.6,0.63, 0.67, 0.793, and 1.0 (with σ representing the diameter of a LJ segment) over the whole range of liquid-vapor coexistence temperatures. The simulated vapor-liquid interfacial tensions for systems with values of the parameters chosen to represent real fluids (e.g., nitrogen, fluorine, chloride, and ethane) are in very good agreement with the experimental data.