Universal Scaling of Pair-Excess Entropy and Diffusion in Strongly Coupled Liquids

Abstract: Understanding diffusion in liquids from properties of static structure is a long standing problem in condensed matter theory. Here we report an atomistic study of excess entropy and diffusion coefficient in a strongly coupled Yukawa liquid. We observe that the pair excess entropy $s_2$ scales with temperature as $-3.285 \;(T_m / T)^{0.665}$ and contributes to about $90\%$ of the total excess entropy close to the freezing transition $T_m$. We further report that at low temperatures where the diffusive transport is mediated by cage relaxation, the diffusion coefficient when expressed in natural units of the Enskog collision frequency and the effective hard sphere diameter, obeys the scaling law $0.04\; e^{s_2}$ and deviates from it at high enough temperatures where cages cannot form. The scaling laws reported here may also apply to strongly coupled dusty plasmas and charged colloids.