
Accession Number : AD0742119
Title : Theory of Surface Atom Mean Square Displacements in Chrominum.
Descriptive Note : Technical rept.,
Corporate Author : CALIFORNIA UNIV IRVINE DEPT OF PHYSICS
Personal Author(s) : Wallis,R. F. ; Cheng,D. J.
Report Date : 28 MAR 1972
Pagination or Media Count : 15
Abstract : The temperature dependence of the mean square displacements for atoms on the (100) and (110) surfaces of chromium has been studied theoretically using the harmonic approximation. Calculations were carried out for crystals with periodic boundary conditions in two directions and free boundary conditions in the third direction using a BornVon Karman model with central interactions up to third nearest neighbors and noncentral angular stiffness interactions between nearest and next nearest neighbors. The values of the force constants were chosen to give good fits to the elastic constants and to the bulk phonon dispersion curves in the three major directions (100), (110) and (111). The ratio of the meansquare displacements at a surface to that in the bulk was calculated as a function of temperature for both the (100) and (100) surfaces. The theoretical results are compared with the available experimental data from lowenergy electron diffraction. (Author)
Descriptors : (*CHROMIUM, PHONONS), (*SURFACES, CHROMIUM), SURFACE PROPERTIES, METAL CRYSTALS, ELECTRON DIFFRACTION, CRYSTAL LATTICES, DISPERSION RELATIONS
Subject Categories : Solid State Physics
Distribution Statement : APPROVED FOR PUBLIC RELEASE