Electronic and bonding properties of TiB2

The structural and electronic properties of TiB2 have been calculated using the first-principles total-energy pseudopotential method based on density functional theory. It is shown that the calculated lattice constants and heat of formation of TiB2 are in good agreement with the experimental results. By analyzing the band structure, density of states and Mulliken population, it is found that the bonding nature in TiB2 is a combination of ionic, covalent and metallic. The 2s–2p interaction exists in the close-packed layer of boron atoms. The hybridization of Ti-3d and B-2p from different layers is the main reason for the creation of pseudogap and results in the strong interlayer covalent bonding. In the same time, the charge transfer from titanium to boron is as significant as 1.16 electrons in the present case. The d–d resonance and free-electron 3d states of titanium atoms contribute to the covalent and metallic bonding in the layer of titanium atoms.