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Phonon Scattering at Multi‐Level Impurities
Author(s) -
Michel H.,
Wagner M.
Publication year - 1978
Publication title -
annalen der physik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.009
H-Index - 68
eISSN - 1521-3889
pISSN - 0003-3804
DOI - 10.1002/andp.19784900604
Subject(s) - phonon , physics , renormalization , quantum tunnelling , scattering , dispersion relation , formalism (music) , condensed matter physics , phonon scattering , quantum mechanics , quantum electrodynamics , art , musical , visual arts
A Green's function technique is used to calculate the dispersion and damping of phonons at tunneling centers with internal degrees of freedom. Starting from a model for tunneling centers oriented in 〈100〉‐orientations, we decouple the evolution hierarchy of Green's functions in second order. A further iteration of the resulting integral equation leads to dispersion and damping. The frequency power law differs for the even and odd parity phonons, which are involved in the local transitions. In a second approach the damping is recalculated by means of a scattering formalism, which steps directly into the fourth order. This direct method shows an extension of the renormalization of the local energy spacings and of the homogeneous linewidths.