First Principle The Vo <sub>-2 </ Sub>, Zns And Fe <sub> 4 </ Sub> N Electronic Structure And Nature

Modern industrial production sets an even higher and higher demand on the raw material properties, and the research of experiments and theory on the material becomes a hot topic. Many experiment jobs have got much higher achievements, but only do combinate experiments and theory,we can make a breakthough on material research fields .In this paper some typical materials are computed theortically in order to interpret, replenish and even predict some theory on material experiments. The ab initio theory as an old and young tool has obtained higher achievement in the material calculation field. Now the using of large and high-speed electronic computers make the advantage of the theory research more and more outstanding. The research of energy band theory is the calculation which develops from qualitative generalized law to complicated energy band of specific materials. There are many arithmetics based on density function theory, such as LCAO-TB,OPW,PWP,LAPW and LMTO, etc. In this paper three common and typical materials, electronic structure and properties are calculated based on the plane-wave pseudo-potential density function method within ab initio theory. And I mainly do three aspects of job.1.Electronic structures of two types of VO2 crystal have been computed by means of plane wave pseudo-potential method with generalized gradient approximation. The density of states(DOS) and energy band structure of the monoclinic crystal in low temperature and the tetragonal crystal in high temperature have been studied. After analysis, the former is of insulator property and the latter of metal property, which are in consist with the existed experiment results. Moreover, by analysis with electronic density of states (DOS) and energy band structure we have found that the different properties attribute to 3d electrons in V atoms and non-local character is different in different structures, which are in consist with others, papers .We have substituted the F atoms for O atoms in the monoclinic crystal and computed the case of substitution doping. The result agrees with the experiment results. We think it is very successful to describe the structure and property of VO₂ by using plane wave pseudo-potential method with generalized approximation. It is a innovation in terms of study method.2.We have calculated electronic structure of zinc blende structure ZnS under different high pressures by means of plane wave pseudo-potential method with generalized gradient approximation based on density function theory. After analysis we have found that parameter lattice constants and bond length decrease with pressure increasing.The charges transferring from S atoms to Zn atoms is less and less,and covalence character of Zn-S bond is stronger. Secondly, the peaks of density of states of Zn atoms and S atoms change to some degree. Furthermore, they have a shifting tendency towards lower energy. On the other hand, ZnS turns to indirect band gap semiconductor from direct band gap one when ambient pressure arrives at 24GPa.The indirect band gap is less and direct band gap is more with pressure increasing. The results afford ZnS experiment research theoretical predict under high pressure circumstances.3. The electronic structure Fe₄N crystal is calculated by means of density function and plane wave pseudo-potential method. We get its density of states, energy band structure, Mulliken charges distribution and magnetic moment of each atom.The magnetic moment of each Fe atom in the corner angle is 2.94μB and the one in the face center is 2.32μB in the body center crystal of Fe₄N. The result agrees well with the experiment. The magnitude difference is explained well by the interaction of Fe atom and N atom in the different place through Mulliken charge distribution and its spin split density of states .