Ab initio calculation of electronic and optical properties of CaNiN nitride and the signature of topological properties

Structural, electronic and optical properties of nitride ternary phase containing nickel (I) and calcium compound CaNiN were investigated in the present work. The calculations were performed using density functional theory (DFT) within generalized gradient approximation (GGA) using scalar relativistic Vanderbilt-type ultrasoft pseudopotentials. Results for the structural properties carried by an optimization process of the volume under no spin polarized and spin polarized show that no spin polarized state is more stable than ferromagnetic (FM) and antiferromagnetic (AFM) states. The total density of state (DOS) and the band structure of CaNiN compound are studied also. The detail analysis of band structure showed that between 0.3 and 0.55 eV gapped Dirac-cones-like band crossings above the Fermi level at M and A momentum points are observed in the bulk band structure. To understand the bonding nature present between Ni, N and Ca in the sample, the electron local function (ELF) is plotted along (110) plane. Additionally, many-body perturbation theory (MBPT) based on one-shot the random phase approximation (RPA) approach is used to obtain some optic properties of the sample including the so-called local field (LF) effects and without local field (NLF) effects, like the complex dielectric function ε(ω) and electron energy loss spectroscopy (EELS).