Abstract
The fundamental optical lattice vibrations are treated as the system, the remaining lattice vibrations as the reservoir, and the anharmonic interactions as the coupling in a general density matrix theory of relaxation processes. An immediate result of this theory are expressions for frequency dependent level shifts and damping coefficients as well as corresponding frequency dependent coupling coefficients between the optical modes. If the coupling coefficients are neglected, and if in our expressions for the shift and damping coefficients anharmonic interactions in the reservoir are neglected our expressions simplify to those obtained by Wallis and Maradudin by summing an infinite ladder of diagrams. By treating an arbitrary mode as the system and using the fluctuation-dissipation theorem, we derive the relation between the lifetime and shift of the mode and its contribution to the one-phonon inelastic neutron scattering line shape. The relaxation theory we use is based on a systematic improvement of the Hartree approximation in which the system and reservoir are treated in a symmetric fashion.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
