Thermodynamic analysis of the classical lattice-hole model of liquids

Abstract

A complete thermodynamic analysis of the classical 2-parameter lattice-hole model of liquids is presented. To our knowledge, no such analysis was available before. It is shown that the model depicts a van der Waals like behavior. The calculated phase diagram features a coexistence line between a condensed and a gas phases ending at a critical point. The model is not able to describe a transition between two condensed phases such as melting. Model parametrization to simulate an archetypal fragile glass forming liquid, the ortho-terphenyl, reveals an only qualitative/semi-quantitative agreement with available experimental information. The extreme simplicity of this 2-parameter model restricts its ability to describe a real liquid. Taking into account the existence of a volume difference between a hole and a molecule, inserting a temperature and pressure dependencies of the physical parameters and allowing the energy parameter to depend on the hole concentration are the most promising modeling options.

The Modified Random Network (MRN) Model within the Configuron Percolation Theory (CPT) of Glass Transition

“…In our case, we applied the set theory to the set of chemical bonds which can be either intact or broken due to thermal fluctuations. In such a way, we are dealing with a typical two-level system that is well developed theoretically as a tool to describe amorphous materials and the glass transition [40,41]. Focusing on just broken bonds termed configurons reveals that at absolute zero T = 0, there are no broken bonds in the glass, whereas at finite temperatures, broken bonds are formed by thermal fluctuations.…”

The Relationship between Free Volume and Cooperative Rearrangement: From the Temperature-Dependent Neutron Total Scattering Experiment of Polystyrene

“…The relationship between the "void" measured by those techniques (such as the positron annihilation lifetime spectroscopy, gas absorption and birefringence measurements) and free volume is hard to judge [7]. In scattering methods, the only experimental observation which may be related to the molecular packing density and possibly the "free volume" has been the small change in the scattering function, S(q), at the scattering vector (q) in the range of the monomer dimension [8]; while in the simulation, some groups have tried to use thermodynamic approaches to calculate the free volume [9][10][11][12] As a result, the William-Landau-Ferry (WLF) theory is often believed to be phenomenological [13,14].…”