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Shell Model Treatment of the Vibrations of Crystals Containing Substitutional Defects. II. On the Theory of Defect‐Induced One‐Phonon Absorption
Author(s) -
Strauch D.
Publication year - 1968
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.19680300210
Subject(s) - phonon , dipole , crystal (programming language) , condensed matter physics , formalism (music) , vibration , absorption (acoustics) , harmonic oscillator , discrete dipole approximation , materials science , physics , molecular physics , quantum mechanics , optics , art , musical , computer science , visual arts , programming language
A formalism for defect‐induced one‐phonon absorption in the harmonic approximation is presented. The influence of charge changes of defects on the crystal dipole moment is twofold: the charges themselves as well as their displacements are perturbed by these changes. Averaging over defect configurations energy shift and width of plane‐wave‐like phonons is obtained. A self‐consistent solution of the perturbed Green's function which takes into account perturbations up to second order in the defect concentration is used. In the homopolar crystals absorption occurs only if the actual (not effective) charges are changed. Comments are made on effective charges and their changes.