Coexistence of low and high overlap phases in a supercooled liquid: An integral equation investigation.
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 ρ (number-density), T (temperature), and inter-replicas couplings ε12. Analysis of the resulting effective (or Landau) potential W(ρ,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 Tcwell above the temperature Toof the "ideal glass" transition observed in the limit ε12→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 Tc, 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 Tcand To.
LCP-A2MC, EA3469, Université de Lorraine, 1 Bd. François Arago, Metz F-57078, France.
Jean-Marc
JM
Bomont
Dipartimento di Fisica, Università di Trieste, Strada Costiera 11, 34151 Trieste, Grignano, Italy.
Giorgio
0000000213075349
G
Pastore
UMR 8234 PHENIX, Université Pierre et Marie Curie, Paris, France and Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom.
Jean-Pierre
JP
Hansen