Electronic structure, bonding, and ground-state properties of AlB2-type transition-metal diborides - art. no. 045115

The electronic structure and ground state properties of AIB(2) type transit ion metal diborides TMB2 (TM = Sc, Ti. V, Cr, Mn, Fe, Y, Zr, Nb, Mo, Hf, Ta ) have been calculated using the self consistent tight-binding linear muffi n-tin orbital method. The equilibrium volume, bulk moduli (B-0), pressure d erivative of bulk moduli (B-0'), cohesive energy (E-coh) heat of formation (DeltaH), and electronic specific heat coefficient (gamma) are calculated f or these systems and compared with the available experimental and other the oretical results. The bonding nature of these diborides is analyzed via the density of states (DOS) histogram as well as the charge density plots, and the chemical stability is analyzed using the band filling principle. The v ariation in the calculated cohesive proper ties of these materials is corre lated with the band filling effect. The existence of a pseudogap in the tot al density of states is found to be a common feature for all these compound s. The reason for the creation of the pseudogap is found to be due to the s trong covalent interaction between boron p states. We have made spin polari zed calculations for CrB2, MnB2, and FeB2 and found that finite magnetic mo ments exist fur MnB2 and CrB2 whereas FeB2 is nonmagnetic.