Some Aspects of the Electronic Structure of Metals.
This work is concerned with a number of applications and fundamental issues in the theory of metals. In the first part, conventional liquid metal transport theory is extended to crystalline simple metals near the melting point. The concept of an ion reference system is introduced for the solid to deal with coherent scattering effects and the ion dynamics are treated beyond the conventional one-phonon approximation by working directly with the ion structure factor. The change in resistivity on melting is calculated for fourteen elements and related to differences in structure between liquid and solid. The identification, during this work, of anomalous features in the structure factor of alkali metals is then pursued. Surveys of this function for several bcc metals are carried out based on lattice dynamical calculations, which reveal specific classes of structure. The origin of these in the phonon spectra is elucidated and their connection to structural phase transitions is discussed. The second part of the work deals with issues relating to the non-uniform electron density in a metal. First, the consistent treatment of static and dynamic properties of metals using interatomic potentials containing volume or mean density dependence is examined. The focus is on the discrepancy in the bulk modulus calculated via the methods of longwaves and homogeneous deformation. A resolution of this long-standing 'compressibility problem' is provided which hinges on taking account of local inhomogeneities in electron density that modulate the interatomic potentials. Finally, the quasiatom model, which provides a practical scheme for treating the embedding energy of an impurity atom in a non-uniform electronic host, is considered. The physical basis of this model is examined by re-deriving the embedding energy of a He atom in the uniform electron gas using an alternate model which focuses on orthogonality effects.
- Pub Date:
- Physics: Condensed Matter