الفهرس 
Theory and Calculations
Effect of Changing the Lattice Parameter on the Magnetic Moment and DOSOnly 14 pages are availabe for public view
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Abstract
This thesis is concerned with calculating, from first-principles, the magnetic moment and electronic structure of selected half-Heusler compounds. The interesting property of half-metallicity has been observed experimentally in several members of the half-Heusler system. This property is technologically important in the field of spintronics, i.e. electronics in which the electron spin is exploited. For this purpose we have used two well-known electronic packages designed for electronic structure calculations from first-principles. There are the DFT-based FPLO and WIEN2K packages. The FPLO has been extensively used throughout the present work whereas the use of WIEN2K has been limited to selected electronic structure calculations. Our calculation is spin-polarized within the Local Density Approximation (LDA). Two groups of half-Heusler compounds have been studied in this work: the first group includes XMnSb, XCrSb and XVSb where X ≡ Ni, Co, Fe, Pd, Pt, Ir and Rh. The second group is NiMnX, NiCrX and NiVX with X one of the SP-elements. In addition we calculated the magnetic moment and electronic structure of selected elements e.g. Cr, V, Fe, Ni, Rh, Pd and Mn in the aforementioned systems. Our calculation demonstrated the existence of half-metallicity in NiMnSb, CoCrSb and CoVSb for example, semiconducting and metallic behavior in the XVSb system with X ≡ Fe and Ni respectively. It is well known that the equilibrium lattice constant of a given system, as calculated by the energy minimization in ab-initio calculation, may differ from the experimental lattice constant. For the sake of investigating the dependence of the magnetic moment and electronic properties on the lattice constant of a given system we have performed this study on the XMnSb, XCrSb and XVSb systems with X ≡ Ni, Co and Fe. Finally we studied the effect of the partial substitution of a 3d element by another 3d element on its properties e.g.YxNi1-xMnSb, where Y ≡ Fe and Cu. Our investigation of the magnetic moment and electronic structure of selected elements e.g. Fe, Sb and Cr, from which the half-Heuster compounds are formed, demonstrates that band magnetism is responsible of the properties we report for these systems. We have compared our results with available experimental and first-principles calculations and found fair agreement.