We propose an explanation for the anomalous compressibility maximum in amorphous silica based on rigidity arguments. The model considers the fact that a network structure will be rigidly compressed in the high-pressure limit, and rigidly taut in the negative pressure limit, but flexible and hence softer at intermediate pressures. We validate the plausibility of this explanation by the analysis of molecular dynamics simulations. In fact this model is quite general, and will apply to any network solid, crystalline or amorphous; there are experimental indications that support this prediction. In contrast to other ideas concerning the compressibility maximum in amorphous silica, the model presented here does not invoke the existence of polyamorphic phase transitions in the glass phase.

We use the example of a study of the compressibility anomaly in amorphous silica to illustrate how molecular-scale simulations can be performed using grid computing. The potential for running many simulations within a single study requires the use of new data management methods, which are discussed in this paper. The example of silica highlights the advantages of the use of grid computing for studying subtle effects.

Grid computing has the potential to revolutionise how small groups of simulation scientists work together to tackle new science problems. In this paper we report how the eMinerals project has developed a small scale integrated compute and data grid infrastructure -the eMinerals minigrid -and developed generic job submission tools that exploit this infrastructure and which enable the science users to also access other grid systems.