The shock response of porous amorphous silica was investigated using classical molecular dynamics, over a range of porosity ranging from fully dense (2.21 g/cc) down to 0.14 g/cc. We observed an enhanced densification in the Hugoniot response at initial porosities above 50%, and the effect increased with increasing porosity. In the lowest initial densities, after an initial compression response, the systems expanded with increased pressure. These results show good agreement with experiments. We explored mechanisms leading to enhanced densification which appear to differ from mechanisms observed in similar studies in silicon.
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