Accession Number : AD0734754

Title :   The Lifetime of Local Phonons in Weakly Anharmonic Linear Lattices.

Descriptive Note : Technical rept. 1 Nov 70-15 Jan 71,

Corporate Author : AIR FORCE WEAPONS LAB KIRTLAND AFB N MEX

Personal Author(s) : Payton,Daniel N. , III

Report Date : OCT 1971

Pagination or Media Count : 27

Abstract : The role of the localized phonon mode has become an important question in the explanation of many physical phenomena associated with disordered and amorphous materials. By using a simple anharmonic model of the linear chain, numerical calculations of the dynamics of steady-state processes have been calculated. A normal mode analysis of the dynamic motions of the atoms in the linear chain yields some approximation to the relative strengths of the phonons of the harmonic lattice in transporting energy through the system. Of particular interest is the decay of the harmonic localized mode created by an isotropic impurity. In the weakly anharmonic system, this higher frequency mode is seen to decay with an observable lifetime. Further calculations yield details of the normal mode coupling at the reservoirs used in the numerical calculations of the lattice thermal conductivity previously reported. (Author)

Descriptors :   (*CRYSTAL LATTICES, THERMAL CONDUCTIVITY), (*PHONONS, EQUATIONS OF MOTION), FOURIER ANALYSIS, VIBRATION, HIGH FREQUENCY

Subject Categories : Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE