| The work done in this thesis is related to electronic band theory, particularly to the application of density functional theory (DFT).; First-principles methods using DFT have proven to be reliable and computationally tractable tools in condensed matter physics. Though DFT methods are very accurate, they are computationally expensive, even with the advance in computing technology. This limits the number of atoms one can simulate using these methods to the order of 100 atoms. This puts severe limitations on using these methods to study properties that require a large number of atoms in the system. Therefore a new methodology needs to be developed.; The NRL TBTE developed by Mehl, Papaconstantopoulos, and others allows to increase the efficiency of methods based on DFT in dealing with systems that involve several thousands of atoms.; My work is related to the application of this method to heavy (sp) materials, tin, lead, polonium, antimony, and bismuth. The resulting TB parameters for these materials are provided in this thesis for use in other type of calculations, such as molecular dynamics simulations. to calculate properties that are temperature dependent. Another contribution of my work is the extension of this method to binary compounds, where I have applied it to NiH and VN. The treatment of the charge transfer occurring in the binaries using this method was also addressed in this work. |
