Abstract
We calculate the dynamic structure factor of liquid Ge -Ge) at temperature and of amorphous Ge -Ge) at using ab initio molecular dynamics. The electronic energy is computed using density-functional theory, primarily in the generalized gradient approximation, together with a plane-wave representation of the wave functions and ultrasoft pseudopotentials. We use a 64-atom cell with periodic boundary conditions, and calculate averages over runs of up to about 16 ps. The calculated liquid agrees qualitatively with that obtained by Hosokawa et al. [Phys. Rev. B 63, 134205 (2001)] using inelastic x-ray scattering. In a-Ge, we find that the calculated is in qualitative agreement with that obtained experimentally by Maley et al. [Phys. Rev. Lett. 56, 1720 (1986)]. Our results suggest that the ab initio approach is sufficient to allow approximate calculations of in both liquid and amorphous materials.
- Received 23 June 2002
DOI:https://doi.org/10.1103/PhysRevB.67.104205
©2003 American Physical Society