Binary Lennard-Jones mixtures with highly asymmetric interactions of the components. 1. Effect of the energy parameters on phase equilibria and properties of liquid-gas interfaces

The molecular dynamics method has been used to investigate liquid-gas phase equilibria in two-component systems containing up to 117000 Lennard-Jones particles. The parameters of the interaction potentials of the mixture components differed only in the ratio of the interaction energies ε22/ε11, which varied from 0.1 to 0.2. Systems with such interaction parameters simulate solutions with limited solubility, in which the second component plays the role of a volatile impurity. The orthobaric densities, saturation pressure, surface tension γ, relative adsorption Γ2(1), and the effective interface thickness have been calculated as functions of the concentration of volatile component in the liquid phase cl in the range of reduced temperatures from T∗ = kBT/ε11 = 0.6 to 1.0. An increase in the adsorption of the volatile component with increasing ratio ε22/ε11 has been established. The isotherms Γ2(1) (cl) and γ(cl) have the following extreme points: maximum Γ2(1) (cl) and minimum γ(cl), whose positions do not coincide.