Some angular force models in the lattice dynamics

SOME ANGULAR FORCE MODELS IN THE LATTICE DYNAMICS (M.Sc. Thesis) Engin DELİGÖZ GAZİ UNIVERSITY INSTITUTE OF SCIENCE AND TECHNOLOGY August 2001 ABSTRACT In this study, theoretical phonon frequences have been calculated along the principal symmetry directions of some cubic metals and alloys by using of the third-neighbours CGW and GTF models. To see the coutribution of the ion-electron interactions on the frequences, Sharma-Joshi scheme is included in the third-neighbours CGW model. The obtained results have been compared with the available experimental data. It is found that CGW and GTF models give the similar results for the bcc structure, and the CGW model for metals and the GTF model for alloys are both superior than others. Science code :500.01.02 Key Words : Lattice dynamics, CGW model, GTF model, Sharma- Joshi model Page Number : ix + 82 Adviser : Prof. Dr. Kemal ÇOLAKO?LU