Physical properties of a GeS2 glass using approximate ab initio molecular dynamics

Abstract

With the use of {\em ab initio} based molecular dynamics simulations we study the structural, dynamical and electronic properties of glassy g-GeS${}_2$ at room temperature. From the radial distribution function we find nearest neighbor distances almost identical to the experimental values and the static structure factor is close to its experimental counterpart. From the Ge-S-Ge bond angle distribution we obtain the correct distribution of corner and edge-sharing GeS${}_4$ tetrahedra. Concerning the dynamical characteristics we find in the mean square displacement of the atoms discontinuous variations corresponding either to the removal of coordination defects around a single particle or to structural rearrangements involving a larger number of atoms. Finally we calculate the vibrational density of states, which exhibits two well separated bands as well as some features characteristic of the amorphous state, and the electronic density of states showing an optical gap of 3.27 eV.

9 pages, 8 figures: to appear in Phys. Rev B

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