Electronic and Magnetic Properties of Ba, Ni and BaNiO$_{3}$: A First-Principles Study

The electronic and magnetic Properties of Ba, Ni and hexagonal crystal structure BaNiO$_{3\, }$have been studied under TB-LMTO ASA method. The space group of compound is P6$_{3}$/mmc and lattice parameters are a$=$b$=$5.62 A$^{^{\circ}\, }$and c$=$4.81 A$^{^{\circ}}$. From our calculation, the minimized lattice parameters of Ba, Ni and BaNiO$_{3\, }$were found to be 5.280 A$^{^{\circ}}$, 3.488 A$^{^{\circ}\, }$and 6.08 A$^{^{\circ}}$ which are at most 1{\%} deviation from the experimental values. Band Structures were determined using the minimized structures which showed the metallic nature of elements Ba and Ni. However, the compound BaNiO$_{3\, \, }$possessed a band gap of 0.95 eV under LDA calculation. Further, U correction was implemented to account for the orbital dependent potential arising largely from the strong correlation of d and f electrons, and the band gap increased to 1.59 eV which is close to the theoretically expected gap ( 1.612 eV ). Density of states showed the ferromagnetic nature of the element nickel with a magnetic moment of 0.59$\mu_{B}_{\, }$close to that of experimental 0.60$\mu_{B}_{,}$ whereas the compound BaNiO$_{3\, \, }$itself was non-magnetic. Finally, a brief study of the charge properties showed the presence of ionic and covalent bonds between the atoms.