Dynamic Structure Factor, Friction and Quasi-Elastic Scattering

CARLOS A. CONDAT; JOSEF JÄCKLE

Proceedings, Third International Conference on Stochastic Structural Dynamics

Universidad de Puerto Rico

Año: 1997; p. 55 - 59

The addition of a stochastic perturbation originates a quasi-elastic line in the  neutron scattering cross section. To investigate the origin of this quasi-elastic component, we present a method to compute the dynamic structure factor S(k,w) for scatterers that are subject to simultaneous potential and stochastic forces. Starting from the suitable Langevin equation, we find an expression for S(k,w) in terms of the solution to a generalized energy diffusion equation. The scattered intensity can then be found by integration. The technique is illustrated by a calculation of the quasi-elastic component for a scatterer subject to weakly anharmonic forces.