Fragility index of a simple liquid from structural inputs

Abstract

We make a first-principles calculation of the fragility index m of a simple liquid with known inter particle interaction. The latter determines the corresponding equilibrium structure factor which is treated as an input in the calculation. Using the density functional theory (DFT) of classical liquids, we determine the configurational entropy at moderate supercooling and extrapolate this data to estimate the Kauzmann temperature TK. The relaxation time for the simple liquid has been obtained from direct solutions of the equations of fluctuating nonlinear hydrodynamics (FNH). These equations also form the basis of the mode coupling theory (MCT) for glassy dynamics. Using the Adam–Gibbs relation, we link the configurational entropy to the relaxation time of the supercooled liquid. The fragility index for the supercooled liquid is estimated from analysis of the curves on the Angell plot.