Structural correlations and phonon density of states in GeSe/sub 2/: A molecular-dynamics study of molten and amorphous states
With use of the molecular-dynamics technique, the structural and dynamical correlations in molten and vitreous GeSe/sub 2/ are investigated with an effective interionic potential which consists of Coulomb, charge-dipole, and steric interactions. It is found that the short-range order is dominated by Ge(Se/sub 1/2/)/sub 4/ tetrahedra and the Ge-Se, Se-Se, and Ge-Ge bond lengths are 2.35, 3.75, and 4.30 A, respectively. The static-structure factor exhibits the first sharp diffraction peak (FSDP)--a characteristic of the intermediate-range order in binary chalcogenide glasses. Partial pair-distribution functions and the corresponding static-structure factors indicate that Ge correlations are responsible for the FSDP, which is in agreement with differential-anomalous-scattering experiments. In the vitreous state, the FSDP displays an anomalous variation with temperature in that its height increases while the other peaks decrease in height upon heating. All the other peaks observed in the structural measurements are also found present in the calculated static-structure factor. The peak positions and their relative heights in the liquid and glass compare favorably with experiments. The calculated phonon density of states in the glass shows peaks at 8.0, 10.8, 26.4, 34.4, and 37.2 meV, which are in good agreement with the positions of the main peaks in inelastic-neutron-scattering experiments. In addition, we find a companion line of the symmetric breathing mode A/sub 1/ (26.4 meV) at 27.8 meV. Raman-scattering experiments also find the companion line to be /similar to/1.5 meV higher than the A/sub 1/ mode.
- Research Organization:
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853-2501
- OSTI ID:
- 6150671
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 39:9; ISSN PRBMD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360602* -- Other Materials-- Structure & Phase Studies
AMORPHOUS STATE
BOND LENGTHS
CHALCOGENIDES
COHERENT SCATTERING
DATA
DIFFRACTION
DIMENSIONS
EXPERIMENTAL DATA
FLUIDS
GERMANIUM COMPOUNDS
GERMANIUM SELENIDES
GLASS
INFORMATION
LENGTH
LIQUIDS
MATHEMATICAL MODELS
MOLECULAR MODELS
MOLTEN SALTS
NEUTRON DIFFRACTION
NUMERICAL DATA
PHONONS
PHYSICAL PROPERTIES
QUASI PARTICLES
SALTS
SCATTERING
SELENIDES
SELENIUM COMPOUNDS