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Coherent‐potential approximation for vibrations in Ga 1— x In x Sb and Ga 1— x In x As mixed crystals
Author(s) -
Kleinert P.
Publication year - 1982
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221140219
Subject(s) - coherent potential approximation , force constant , lattice vibration , dielectric , condensed matter physics , mode (computer interface) , interpolation (computer graphics) , lattice (music) , vibration , function (biology) , physics , crystal (programming language) , lattice constant , constant (computer programming) , mixed mode , dielectric function , line (geometry) , materials science , quantum mechanics , phonon , mathematics , classical mechanics , geometry , electronic structure , molecule , motion (physics) , computer science , acoustics , composite material , biology , operating system , evolutionary biology , diffraction , programming language
The vibrational properties of the mixed crystals Ga 1— x In x As and Ga 1— x In x Sb are investigated using the coherent‐potential approximation (CPA). These III—V systems switch from one‐mode to two‐mode behaviour as the composition is changed. Results are obtained for a one‐dimensional model including self‐consistently mass defects and force constant changes. The calculated density of states and the dielectric susceptibility are compared with results of the mass CPA. In addition, a three‐dimensional CPA Bethe lattice treatment is carried out to calculate the optical properties of these disordered systems showing mixed‐mode behaviour. The force‐constant change is included by a virtual‐crystal interpolation. The theory explains the mode switching behaviour and agrees fairly well with experimental peak positions and line shapes of the response function.