Coexistence of low and high overlap phases in a supercooled liquid: An integral equation investigation

摘要

The pair structure, free energy, and configurational overlap order parameter Q of an annealed system of two weakly coupled replicas of a supercooled " soft sphere" fluid are determined by solving the hypernetted-chain (HNC) and self-consistent Rogers-Young (RY) integral equations over a wide range of thermodynamic conditions rho (number-density), T (temperature), and inter-replicas couplings epsilon(12). Analysis of the resulting effective (or Landau) potential W(rho, T; Q) and of its derivative with respect to Q confirms the existence of a "precursor transition" between weak and strong overlap phases below a critical temperature T-c well above the temperature T-o of the " ideal glass" transition observed in the limit epsilon(12) -> 0. The precursor transition is signalled by a loss of convexity of the potential W(Q) and by a concomitant discontinuity of the order parameter Q just below T-c, which crosses over to a mean-field-like van der Waals loop at lower temperatures. The HNC and RY equations lead to the same phase transition scenario, with quantitative differences in the predicted temperatures T-c and T-o. Published by AIP Publishing.