Study of Bond Strengths in Metals Using Localized Functions.

摘要

The possibility of using Wannier functions in the theory of the energy of metals is important because it would greatly simplify the analysis of local interactions involved in defect formation, diffusion, ordering and precipitation. The objective of this study was to determine to what extent such localized functions could be applied to metals. This study began with the development of a general formalism that showed how to construct quasi-Wannier localized functions for nonperiodic as well as crystalline systems, and to incorporate such functions in cohesive energy theory. The theory was applied to the alkali metals, alkaline earth metals and cadmium, to successfully describe the cohesive energy, lattice parameter, compressibility and equation of state. The conclusion was that the method is practical, and localized functions can indeed be used in metals. A model was proposed, the 'rigid Wannier function' model, which would greatly simplify calculations in distorted crystals. The model gives a reasonable representation of the electron density around point defects in ideal methods. It is currently being applied to phonon spectra and relaxation of atoms around an impurity. This work will continue even though the contract period is over. (Author)