Phonon dispersions in Ga x Al 1 − <mml:mi …
1990; American Physical Society; Volume: 65; Issue: 1 Linguagem: Inglês
10.1103/physrevlett.65.84
ISSN1092-0145
AutoresStefano Baroni, Stefano de Gironcoli, Paolo Giannozzi,
Tópico(s)Thermal properties of materials
ResumoThe vibrational properties of ${\mathrm{Ga}}_{\mathit{x}}$${\mathrm{Al}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As alloys have been studied using large supercells to simulate the disorder and ab initio interatomic force constants. In agreement with recent experimental evidence, our results indicate that well defined GaAs-like and AlAs-like phonon dispersions exist for any concentration. Besides broadening phonon states with definite wave vector, alloying narrows the optic branches and lowers the longitudinal modes more than the transverse ones, thus reducing the LO-TO splitting. The acoustic bands are instead rather insensitive to the composition.
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