First-principles Studies On The Topological Theory And The Spin Chirality Of The ?-? And ?-? Compounds

The ?-?-types and ?-?-types narrow gap semiconductors have attracted great attention these years.The properties of the Hg-?,Zn-? and the Ga-V compounds is the widely study.However,the research of the topological property is rare.Therefore it is natural to ask if the relationship between the band structure and states transformation is general or not.The study of the band structure has benefited from the related numerical algorithms theory and the development of computer technology.The first-principles calculation of density functional theory,it has been conventional research methods in materials science of the condensed matter physics,quantum chemistry and materials.The ?-?and ?-? compounds of the band structure under the different pressure and doping are study by the first-principles principle of density functional theory.As for summarized are the follows:(1)Based on the electron band structure of ?-? and ?-? compounds reversal band-order as follows:Normal insulators(NIs),it shows that the conduction band min-imum at is mostly from cation s-orbital of ZnO,CdTe,and GaN in absence of SOC,which the valence band maximum is mostly form anion p-orbital.As for TIs,their s-orbital-like bands lies below p-orbital-like bands,which mean that the conduction band minimum at is mostly from anion p-orbital,while the valence band maximum is mostly from cation s-orbital,which show that a non-trivial band structure of caused by tetrahedra crystal field(CF)in zinc-blend phase and wurtzite phase.(2)The study of the transformation of Hg-? and Tl-? topological insulator com-pounds by pressure and doping.It is revealed that the relationship between the atomic spin-orbit coupling(SOC)and the atomic p-d hybridization(p-dH)plays a decisive role in the topological phase transition.(3)The study of the chirality of Hg-VI and Tl-V topological insulator compounds by pressure and doping.It is revealed that the right-handed topological materials in the TIs with p-dH near the Fermi energy.(4)The band structure of ?-?-?2-?4 compounds by the first-principles calculation,it is revealed that the atomic d-orbital plays a decisive role of the optical properties in the ?-?-?2-?4 materials.Based on this study,we can reveal that the atomic radius,molecular bond length and the lattice spacing can affect the properties of solid materials by changes such as electric dipoles,orbital coupling,and electronic localization;Therefore the academia and industry have to face up to these small parameters,than they can control the physical properties of materials to meet our application requirements by adsorption,doping and pressure in the future.