Direct Molecular Dynamic Simulation of Light-Induced Structural Change in Amorphous Selenium

An amorphous selenium network structure was constructed by combination of a lattice random walk and ab initio molecular dynamic (MD) simulation. The static structure factor, pair correlation function, and vibrational and electronic density of states simultaneously agree with experiment. For the first time, we study structural rearrangement due to light-induced changes in occupation. The predictions of the Kastner et al. valence alternation model are essentially confirmed, and new features of the rearrangement are elucidated. The structural rearrangements are less local than in simple models.