Model Potential Studies of Perfect and Defect Properties of Some Alkali Metal Hydride and Deuteride Crystals

Abstract

The work in this thesis describes an investigation of the static, dynamic, and defect properties of hydride and deuterides of lighter lithium in addition to a heavier sodium alkali metal. A combination of various theoretical techniques is utilized to obtain a potential model that gives a good unified description of all the properties, e.g., static, dynamic, and defect properties of the lighter as well as the least studied heavier compounds. The first part of the work reviews the directions along which the study on crystal interactions is progressing on the basis of the phenomenological and microsc6pic theories. The basic theories of these models have been reviewed with a view to developing an interaction potential applicable in all respects in the field of alkali metal hydride and deuterides. The second part of the work is concerned with the development of a set of inter ionic potentials of the Born-Mayer form using the shell model. Some of the earlier potentials suffer from serious drawbacks particularly when applied to dynamic and defect properties. These deficiencies are taken into consideration in the present study. The development is carried out through using a combination of theoretical techniques, empirical fit, and a few plausible assumptions…………………..