Impurity pair modes in a diatomic linear chain

15 November 1975

journal article
research article
Published by American Physical Society (APS) in Physical Review B

Vol. 12 (10) , 4547-4552
https://doi.org/10.1103/physrevb.12.4547

Abstract

The modes of vibration of pair of mass-defect impurities occupying next-nearest-neighbor positions in a diatomic linear chain are examined using the Green's-function method. The existence of new localized, gap, and inband resonant modes corresponding to pairs of light, heavy, and a combination of light and heavy impurities, respectively, is predicted. The calculations are carried out for two different cases; first, for a pair of impurities in the heavy host sublattice and secondly, for the case when the impurity pair is substituted in the light host sublattice. The Lucovsky-Brodsky-Burstein criterion is used for applying the theory to three-dimensional crystals. The localized and gap pair mode frequencies thus estimated for different impurities in KI, KCl, and NaCl hosts show qualitative agreement with the corresponding experimental values.

Keywords

THREE DIMENSIONAL

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