الفهرس 
ACKNOWLEDGMENTOnly 14 pages are availabe for public view
 |  | from | 146 |  |  |
| | | from | 146 | | |
Abstract
This thesis is concerned with calculating, from first-principles, the electronic structure, elastic properties and magnetic properties of selected half- metallic compounds. We report on two compounds: MgN compound from the alkaline earth nitrides family and GdN from the interesting rare earth nitrides compounds. These half-metallic compounds are interesting both on the fundamental and application levels e.g. spintronic applications For this purpose we have used two well-known electronic structure packages designed for electronic structure calculations from first-principles, namely the DFT-based FPLO (FPLO.09 version) and WIEN2K packages. We have used both of the Local Spin Density (LSDA) and the Generalized Gradient approximations (GGA). We have studied the electronic and magnetic properties for two possible crystal structures of MgN: Rock-Salt (RS) and Zinc Blende (ZB). For the two structures, we have calculated the lattice constant, magnetic moment, energy gap, spin polarization, bulk modulus and its pressure derivative. Both of the magnetic moment and the energy gap were calculated in the scalar and relativistic schemes. Four different forms of equation of state have been used to fit our ab initio data of the energy dependence on the unit cell volume. The electronic, elastic and the magnetic properties of GdN in its three possible crystal structures (RS, CsCl, and ZB) were studied. The energy dependence on the unit cell volume data were fitted by using the modified Birch-Murnghan equation of state. We have predicted three phase transitions: from ZB to RS, RS to CsCl and ZB to CsCl. The density of states and the band structures of GdN show the half-metallic behavior only in both of the ZB and the RS structures. We have compared our results for MgN and GdN with available experimental and first-principles calculations and found fair agreement.