DFT calculation of vibrational frequencies of clusters in GaAs and the Raman spectra.
We have calculated the vibrational frequencies of clusters of Ga and As atoms from the first principles using the density-functional theory (DFT) method and the local-density approximation (LDA). We find that the calculated value of 286.2 cm(-1) for a linear cluster of Ga(2)As(2) is very near the experimental value of 292 ± 4 cm(-1). The calculated value of 289.4 cm(-1) for Ga(2)As(6) (dumb bell) cluster is indeed very near the experimental value. There are strong phonon correlations so that the cluster frequency is within the dispersion relation of the crystal LO value. There is a weak line in the experimental Raman spectrum at 268 cm(-1) which is very near the value of 267.3 cm(-1) calculated for the Ga(2)As (triangular) cluster. The weak lines corresponding to the linear bonds provide the strength to the amorphous samples. There are clusters of atoms in the glassy state of GaAs.
MLR Institute of Technology, Affiliated to Jawaharlal Nehru Technological University, Dundigal, Hyderabad 500043, India.
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V
Radhika Devi
Keshav N
KN
Shrivastava
D001152:Arsenicals / Q000737:chemistry*; D005708:Gallium / Q000737:chemistry*; D008958:Models, Molecular; D060739:Phonons; D011789:Quantum Theory; D013059:Spectrum Analysis, Raman; D014732:Vibration
D001152:Arsenicals; C043055:gallium arsenide; D005708:Gallium