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Tor Grande

Publications and source records attributed to Tor Grande.

2 recordsLinked to original sources

Simulated silica.

We review how molecular dynamics computer simulations are providing a comprehensive picture of the behaviour of silica, as modelled by the van Beest-Kramer-van Santen (BKS) potential. We have recently evaluated a number of key properties of this model system: the phase diagram, including melting lines of three crystal phases; the equation of state and free energy of the liquid phase; the dynamical equation of state; the average energy of inherent structures, and configurational entropy, associated with the potential energy landscape of the liquid; and a characterization of the local coordination environments in the supercooled liquid. The results reveal the interplay among a number of phenomena, in particular, the relationship between the energy landscape and the fragile-to-strong crossover of the liquid dynamics; and the relation of both of these to the possibility of a liquid-liquid phase transition in the supercooled liquid.

Computer Simulation↗

Phase diagram of silica from computer simulation.

We evaluate the phase diagram of the "BKS" potential [Phys. Rev. Lett. 64, 1955 (1990)]], a model of silica widely used in molecular dynamics (MD) simulations. We conduct MD simulations of the liquid, and three crystals ( beta -quartz, coesite, and stishovite) over wide ranges of temperature and density, and evaluate the total Gibbs free energy of each phase. The phase boundaries are determined by the intersection of these free energy surfaces. Not unexpectedly for a classical pair potential, our results reveal quantitative discrepancies between the locations of the BKS and real silica phase boundaries. At the same time, we find that the topology of the real phase diagram is reproduced, confirming that the BKS model provides a satisfactory qualitative description of a silicalike material. We also compare the phase boundaries with the locations of liquid-state thermodynamic anomalies identified in previous studies of the BKS model.

Journal Article↗