The breakdown of the direct relation between the density scaling exponent and the intermolecular interaction potential for molecular systems with purely repulsive intermolecular forces

Abstract

In this work, we question the generally accepted statement that the character of intermolecular interactions can be directly determined from the scaling exponent. Based on detailed studies of polyatomic molecular systems with precisely defined and purely repulsive intermolecular potential, we show that the value of the density scaling exponent evidently differs from the one predicted by the intermolecular virial-potential-energy correlation. Since the latter value directly results from the intermolecular potential, information on the interactions between molecules within the system cannot be immediately gained from the density scaling exponent value. Moreover, we suggest that the recently proposed "molecular force" method also returns the value that varies from the one scaling the dynamics. Finally, basing on our results, it might be deduced that the intramolecular interactions influence the density scaling value for real liquids.