iB2结构和性质的第一性原理计算

he electronic, optical, and lattice dynamic properties of hexagonal TiB2 crystal have been calculated using first principle based on density functional theory. It is shown TiB2 has a metallic character indicated by the band structure and the density of states. The conduction bands are mainly composed by anti-bond states of B plane and 3d bands of Ti. In B plane, σbonds are formed by hybirdigation of 2s and 2p orbital. But 2pz responds for delocalized π bond. These states are directly related to the optical transitions as shown in absorption spectrum. Population analysis clearly shows that a similar charge transfer mechanism from 3d of Ti to 2p of B occurred as well as in MgB2. Lattice dynamical results reveal a remarkable splitting effect between LA(LO) and TA(TO). These vibrational modes which located at B hexagonal plane are made up of high frequency part in phonon spectrum. All of the nine eigen values at Γ point are summarized and labeled according to their frequency, The prediction of TiB2 superconducting temperature should be 0 K according to the phonon calculated results.