Quasielastic neutron scattering from anharmonic oscillators subject to weak frictional forces

C.A. CONDAT; J. JÄCKLE

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

The American Physical Society

Año: 1995 vol. 52 p. 6238 - 6246

0163-1829

A Fokker-Planck approach is used to calculate the quasielastic line in the dynamic structure factor fore a one-dimensional harmonic oscillator subject to weak frictional forces. The problem is reduced to solving a diffusion equation in energy space. A general eigenfunction methods of solution is developed using the exact solution to the harmonic oscillator as a guide. It is shown that energy relaxation speeds up, inducing a broadening of the quasielastic line, if a small positive anharmonic term is added to the harmonic potential. The method is then applied to analyze a model embodying essential properties of the soft potentials used in the study of glasses and undercooled liquids.