Theoretical investigation of electronic structure and optical properties of paramagnetic non-oxide perovskite AlCNi3

The electronic structure and optical properties of intermetallic non-oxide perovskite AlCNi3 have been studied, using full-potential augmented plane waves plus local orbitals method. Calculations employing local density approximation (LDA) for the exchange-correlation potential also overestimate the equilibrium lattice constant. It is found that the states near the Fermi level (EF) are dominated by Ni 3d character. The Ni 3d derived peak in the density of states (DOS) close to the EF, is farthest away (∼0.5 eV) from the Fermi level in AlCNi3, compared to the DOS of the other isostructural compounds, MgCNi3 and ZnCNi3. Our calculations show that increase in the lattice constant gives rise to shift in the position of the peak in the DOS towards the Fermi level and a consequent increase in the magnitude of the the density of states at the Fermi level (N(EF)). The calculated optical properties show that the main transitions responsible for the structures in the optical functions studied arise mainly from the Ni 3d states below EF to the hybridized Ni 3d and C 2p states above EF. The implications of the results are discussed.