EXAFS measurements for liquid Ge–Si alloys (original) (raw)

Initio Studies of Liquid and Amorphous Ge

2004

We review our previous work on the dynamic structure factor S(k,ω) of liquid Ge ("-Ge) at temperature T = 1250 K, and of amorphous Ge (a-Ge) at T = 300 K, using ab initio molecular dynamics [Phys. Rev. B67, 104205 (2003)]. The electronic energy is computed using densityfunctional theory, primarily in the generalized gradient approximation, together with a plane wave representation of the wave functions and ultra-soft 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 S(k,ω) agrees qualitatively with that obtained by Hosokawa et al, using inelastic X-ray scattering. In a-Ge, we find that the calculated S(k,ω) is in qualitative agreement with that obtained experimentally by Maley et al. Our results suggest that the ab initio approach is sufficient to allow approximate calculations of S(k,ω) in both liquid and amorphous materials. ∗ Electronic address: jdchai@wam.umd.edu † Electron...