Dynamic Structure Factor of Liquid and Amorphous Ge From Ab Initio Simulations

Abstract

We calculate the dynamic structure factor S(k,omega) of liquid Ge (l-Ge) at temperature T = 1250 K, and of amorphous Ge (a-Ge) at T = 300 K, 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 ultra-soft pseudopotentials. We use a 64-atom cell with periodic boundary conditions, and calculate averages over runs of up to 16 ps. The calculated liquid S(k,omega) agrees qualitatively with that obtained by Hosokawa et al, using inelastic X-ray scattering. In a-Ge, we find that the calculated S(k,omega) 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,omega) in both liquid and amorphous materials.

31 pages and 8 figures. Accepted for Phys. Rev. B

References in corpus (1)

• Vibrational spectrum of topologically disordered systems

Cited by in corpus (8)

• Anharmonic lattice dynamics in large thermodynamic ensembles with machine-learning force fields: CsPbBr${}_3$ a phonon-liquid with Cs rattlers
• Structural and dynamical properties of liquid Si. An orbital-free molecular dynamics study
• An \emph{ab initio} method for locating characteristic potential energy minima of liquids
• Structure and dynamics of l-Ge: Neutron scattering experiments and ab initio molecular dynamics simulations
• Liquid state properties from first principles DFT calculations: Static properties
• Statistical mechanics model for the transit free energy of monatomic liquids
• An improved model for the transit entropy of monatomic liquids
• Voronoi Construction for Improving Numerical Calculations of Particles