Local structure in sub- and supercritical CO 2: A Voronoi polyhedra analysis study

Abstract

The local structure of CO 2 along the liquid–gas coexistence curve and along the critical isochore is analyzed through the metric properties of the Voronoi polyhedra (VP) of the molecules, such as the volume, density, and asphericity of the VP as well as the radius of the vacancies between the molecules. The behaviour of these properties (i.e., their distributions as well as the associated average and fluctuation values) provides a clear evidence of the inhomogeneous character of the distribution of the CO 2 molecules in the system when the temperature becomes close the critical one.