Elastic Characterization of S- and P-Wave Velocities in Marinelike Silica: The Role of Nonequilibrium Molecular Dynamics

The alpha-quartz polymorph of SiO2 forms the basis of mineral sands stable down to 100 km depths below the surface, making it of central geoscientific relevance. The characterization of the nanoscale properties of these materials is of importance, especially for elastic properties governing phonon and sound propagation, and is of very high industrial relevance for oil exploration. Here, for the first time, we apply non-equilibrium molecular dynamics simulation to analyze the propagation of an artificial velocity perturbation in silica systems and, in so doing, determine S- and P-wave velocities in a manner redolent of concept to seismic-based oil-exploration approaches. This propagation has been analyzed systematically by means of different metrics in terms of spatiotemporal system response; these produce consistent results, by and large. In particular, we find excellent quantitative agreement with experimental S- and P-wave velocities, in many cases.