Structural and electronic properties of the A-15 compounds Nb3Rh and Nb3Ir

The structural and electronic properties of the A-15 compounds Nb3Rh and Nb3Ir were studied by means of escalar relativistic full-potential linearized augmented-plane wave (FP-LAPW) calculations with generalized gradient corrections. An investigation of the band structure of the hypothetical Nb3Nb compound was also performed at the theoretical equilibrium lattice constant to ascertain the contribution of the nontransition elements on the B site in these A3B-type compounds. Band structures and total densities of states were obtained. A rough estimate of the electron-phonon coupling parameter λ as well as of the electronic specific-heat coefficient γ were obtained for both Nb3Rh and Nb3Nb, which confirms that this latter is a low-temperature superconductor with Tc≲10K.