One of the challenging problems related to the liquid-glass transition phenomenon is establishing a link between the character of intermolecular interactions and the behavior of molecular dynamics. Introducing the density scaling concept, according to which dynamic quantities, e.g., viscosity or structural relaxation time (${\tau }_{\alpha }$) measured at different thermodynamic conditions are expressed as a single universal curve if plotted against ${\rho }^{\gamma }/T$, led to significant progress in solving this problem since the scaling exponent $\gamma$ defines the steepness of the repulsive part of the intermolecular potential. Herein, we found that relaxation dynamics of van der Waals and H-bonding glass formers, for which the Kirkwood factor ($g_K$) is an isomorph-invariant quantity, satisfy an alternative scaling, $\log {\tau }_{\alpha }$ vs $T{(\mathrm{\Delta }{ϵ}_{s}T)}^{-\gamma }$. As a result, the exponent $\gamma$ is determined from the temperature and pressure evolutions of ${\tau }_{\alpha }$ and dielectric relaxation strength $\mathrm{\Delta }ϵ$—both obtained in a single dielectric experiment, which makes the $\gamma$ coefficient to be accessed in the future for an extensive database of glass-forming liquids.

• Received 20 February 2023
• Revised 14 July 2023
• Accepted 25 July 2023

DOI:https://doi.org/10.1103/PhysRevLett.131.086101