A plausible interpretation of the density scaling of the diffusivity in viscous liquids

TL;DR

This paper presents an analytical model linking the density scaling of diffusivity in viscous liquids to thermodynamic properties, specifically relating the scaling exponent to the pressure derivative of the bulk modulus, and compares results with simulations.

Contribution

It introduces a new analytical second-order polynomial model that connects diffusivity scaling to thermodynamic parameters, expanding understanding of viscous liquids.

Findings

The model accurately describes the density scaling of diffusivity.

The scaling exponent correlates with the pressure derivative of the bulk modulus.

Results are consistent with computer simulation data.

Abstract

Fundamental thermodynamic concepts and an earlier elastic solid-state point defect model are employed to formulate an analytical second-order olynomial function describing the density scaling of the diffusion coefficient in viscous liquids. The scaling exponent is correlated, within the approximations made in the present approach, with the pressure derivative of the isothermal bulk modulus. Our findings are compared with computer simulation results.