Borosilicate glass potentials for radiation damage simulations

Three borosilicate glass (SiO2-B2O3) fixed charge potentials from the literature are compared (Delaye and Ghaleb, 1996; Kieu et al., 2011; Rushton, 2006) and their suitability for use in simulations of radiation damage is assessed.For a range of densities, we generate glass structures by quenching at 5×1012 K/s using constant volume Molecular Dynamics. In each case, the bond lengths, mean bond angles, bulk modulus, melting point and displacement energy thresholds are calculated, and where possible compared to experimental data. Whereas the bond lengths and mean bond angles are reasonably well predicted, we find that the potentials predict melting temperatures, bulk moduli and densities that are higher than experimental data.The displacement energy thresholds are generally lower than those for ionic crystalline materials, but show a wider spread of values. However, the barriers for atomic rearrangements, after atoms have been displaced in the equilibrium structures, are very high. This indicates, that the radiation damage produced in the ballistic phase of a collision cascade, is likely to persist for extended time scales. This is in contrast to crystals, where interstitials and vacancies can diffuse rapidly between successive radiation events.