Accession Number : AD0290090

Title :   EVALUATION OF THE VAN HOVE CORRELATION FUNCTIONS FOR CERTAIN PHYSICAL SYSTEMS

Corporate Author : AEROSPACE CORP EL SEGUNDO CALIF

Personal Author(s) : DEBAR,ROGER B.

Report Date : 15 OCT 1962

Pagination or Media Count : 1

Abstract : The space and time Fourier transforms of the Van Hove correlation function are evaluated for the cases of coherent scattering from simple crystals and, in a 'quantum hydrodynamics' approximation, from liquid helium. A compact approximate expression for the one-phonon part of the crystal correlation function transform is given, and the contribution of the two-phonon term is considered. A new method of obtaining quantum-mechanical corrections to the classical expression for the Van Hove self-correlation function is discussed, and the result is shown to be of greater potential accuracy than those previously given in the literature. As a test, the prescription is applied to the Langevin equation result for the classical correlation function, and the product is found to differ significantly from recent results, but to be in agreement with an older expression obtained by Vineyard. (Author)

Descriptors :   *FUNCTIONS(MATHEMATICS), *QUANTUM THEORY, CRYSTALS, DENSITY, ENERGY, EQUATIONS, FLUID FLOW, HEAT TRANSFER, HELIUM BOMBARDMENT, PHONONS, SCATTERING

Distribution Statement : APPROVED FOR PUBLIC RELEASE