Direct calculation of light-induced structural change and diffusive motion in glassy As2Se3

Photostructural change of glassy As2Se3 was simulated on an experimentally credible model with excited electronic dynamics within first-principles molecular dynamics. Bond breaking and bond switching reactions account for local changes around defect sites at the short time phase of illumination. For longtime relaxation, defect pairs associated with band tail states become involved in a rearrangement in the network, giving rise to a low energy, nonlocal polaronlike collective oscillation. Diffusive motion is observed for short times, which we tentatively interpret as the initial phase of athermal photomelting.