Electronic Structure of Transition-metal Pnictides Oxides La3T4As4O2 Phase (T = Ni, Cu) from ab-initio Calculations

Electronic structure of the recently synthesized compounds La3T4As4O2 (T = Ni, Cu) are studied using the ab-initio APW+ lo method. A careful analysis of band structures and Fermi surfaces via the Local Density Approximation (LDA), the Generalized Gradient Approximation (GGA) and with the on-site Hubbard Ueff parameter (LDA/GGA + U) was performed. Calculations show that the GGA perfectly reproduces the ground state properties such as lattice constants, internal parameters, interatomic distances, angles, band structures and Fermi surfaces. The relationship between the “1111” and “122” structure types and “3442” structure is indicated and discussed. The GGA calculations show that the lattice constants (a0 and c0) satisfy the intergrowth conditions of the “3442” structure. We found a topological similarity between the Fermi surfaces of Ni-3442 and Ni-1111 systems, which respect the five band model.