# Intermolecular distance and density scaling of dynamics in molecular liquids

## TL;DR

This paper investigates how the dynamics of molecular liquids scale with intermolecular distance and density, revealing that the scaling exponent depends on molecular structure rather than the interatomic potential.

## Contribution

It introduces a new relation for the density scaling exponent in molecular liquids, linking it to molecular structure through the parameter {\delta}.

## Key findings

- The scaling exponent {\gamma} equals n/{\delta} in molecular liquids.
- {\delta} depends solely on molecular structure, not on the interatomic potential.
- Density scaling applies broadly to molecular liquids with rigid bonds.

## Abstract

A broad variety of liquids conform to density scaling: relaxation times expressed as a function of the ratio of temperature to density, the latter raised to a material constant {\gamma}. For atomic liquids interacting only through simple pair potentials, the exponent {\gamma} is very nearly equal to n/3, where n is the steepness of the intermolecular potential, while for molecular liquids having rigid bonds and built using the same interatomic potential, {\gamma}>n/3. We find that for this class of molecular liquids {\gamma}=n/{\delta}, where the parameter {\delta} relates the intermolecular distance to the density along an isomorph (line of approximately constant dynamics and structure). {\delta} depends only on the molecular structure and not the interatomic potential.

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Source: https://tomesphere.com/paper/1904.02026