Effect of Inert Gas Vibrations in Bound States on the Equilibrium of a Vapor-Liquid System

Abstract

The effect the vibrational motion of inert gas atoms in the bound states at an arbitrary density of a vapor–liquid system has on the equilibrium concentration dependence of the chemical potential on density is considered for the first time. Both the potential energy of interaction between atoms and their vibrations in the bound states, starting from an isolated dimer to a dense phase, are considered. Calculations are made using the lattice gas model (LGM) for a one-dimensional fluid. Spatial atomic distributions are described in a quasi-chemical approximation. Local frequencies of atoms are calculated in a quasi-dimer model of vibrational motion. At the same time, the translational motion of atoms when they move to neighboring vacant cells are considered. The calculations are made in two versions of the theory: discrete and continuum. The latter reflects the motion of the center of mass inside the cells into which the entire volume is partitioned in the LGM. It is found that allowing for the vibrations of atoms in the bound states at a fixed density of the system shifts the chemical potential to lower values.