Coarse-grained theory of a realistic tetrahedral liquid model

¹ Department of Chemical Physics, The Weizmann Institute of Science - Rehovot 76100, Israel
² Theoretical Division and CNLS, Los Alamos National Laboratory - Los Alamos 87545, NM, USA

^a ido.regev@gmail.com

Received: 28 October 2011
Accepted: 3 January 2012

Abstract

Tetrahedral liquids such as water and silica-melt show unusual thermodynamic behavior such as a density maximum and an increase in specific heat when cooled to low temperatures. Previous work had shown that Monte Carlo and mean-field solutions of a lattice model can exhibit these anomalous properties with or without a phase transition, depending on the values of the different terms in the Hamiltonian. Here we use a somewhat different approach, where we start from a very popular empirical model of tetrahedral liquids —the Stillinger-Weber model— and construct a coarse-grained theory which directly quantifies the local structure of the liquid as a function of volume and temperature. We compare the theory to molecular-dynamics simulations and show that the theory can rationalize the simulation results and the anomalous behavior.