Communication: Relationships between Intermolecular potential, thermodynamics, and dynamic scaling in viscous systems

Abstract

In this communication, we provide a recipe for a consistent relation between dynamic scaling and thermodynamic properties well-grounded by the same intermolecular generalized Lennard-Jones potential, which is derived by using an essentially modified Avramov model within the framework of the "thermodynamic scaling" idea. This relation is experimentally verified very well for supercooled van der Waals liquids, and consequently, it can be a good basis for a proper universal description of molecular dynamics and thermodynamics of viscous systems.

Glass Transition Temperature and Density Scaling in Cumene at Very High Pressure

“…It has helped lead to the classification of certain liquids as "strongly correlating" and the development of isomorph theory in which many properties of correlating liquids are invariant under conditions of constant ρ γ /T [22][23][24]. Furthermore, the exponent γ is theorized to provide a critical quantitative connection between cooperative dynamics and the intermolecular potential [20,25,26]. Though this scaling behavior has been found to hold over broad dynamic ranges, most tests of Eq.…”

Communication: Thermodynamic scaling of the Debye process in primary alcohols

“…[10][11][12] It is worth noting that theoretical grounds for the thermodynamic scaling is still under consideration. As an example, the mentioned role of the LJ potential or its IPL approximation can also be more complex 13,14 if one takes into account a considerable difference in the values of two scaling exponents, which can be established for a given material: the first one that enables to scale dynamic quantities such as primary relaxation time and viscosity in the way described just below, and the other one that leads to some recently found density scaling of presure-volume-temperature (PVT) data. 15 Nevertheless, each theoretical idea for the thermodynamic scaling is based on experimental findings that structural relaxation times, τ α , (or viscosity) measured isothermally or isobarically can be expressed as a unique function of temperature and volume, TV γ , with exponent γ treated as a material constant.…”

Scaling of volumetric data in model systems based on the Lennard-Jones potential

“…Equation (7), in which, besides the scaling exponents, there is the Grüneisen constant γ G and one of the parameters of Eq. (6), has been earlier proposed by us [31] to explain the considerable discrepancy between γ and γ EOS observed for real materials.…”

“…Recently, this relation has been successfully used by us to analyze the scaling exponents mainly for supercooled van der Waals liquids [25,26,31], and for a supercooled ionic liquid [26,32] and a polymer melt [26] as well. However, a test using simulation data is needed.…”

“…[25], only slightly affect the very good numerical correspondence of these EOS found in the pυT data range of interest. However, the expected correspondence γ EOS ≈ γ IPL has not been undoubtedly proven yet [24][25][26]28,31,32]. In this article, these EOS, given by Eqs.…”