M Bauchy, M Micoulaut
Physical review letters 110 (9), 095501
Publication year: 2013

Topological rigid constraints can be computed rather simply with changing composition and temperature but their estimation remains challenging for other thermodynamic variables. Here, the investigation of densified silicate liquids from molecular dynamics simulations combined with an analysis of radial and angular atomic excursions allows defining a pressure dependence of such constraints. Results show, that for a given composition, the dependence is nonmonotonic as it depends on the interplay between constraints broken by thermal activation and additional constraints arising from the increase of network connectivity under pressure. An anomalous behavior for oxygen bending constraints is obtained in the (P, T) map which connects to reported anomalies in transport properties and is identified as the pressure analogue of the stress-free Boolchand intermediate phase in rigidity driven by composition.