Calculation of the electronic structure of the intermetallic compounds ErNi$_{5-x}$Al$_x$ ($x$ = 0, 1, 2)

The evolution of the electronic structure of the intermetallic compounds ErNi$_{5-x}$Al$_x$ ($x$ = 0, 1, 2) with different positions of the substitution of aluminum atoms for nickel atoms has been investigated. For this purpose, spin-polarized calculations of the energy band spectra of these compounds have been performed using the LSDA + U method, which in the local spin density approximation takes into account strong electron correlations in the 4$f$ shell of the erbium ion. Variants of the substitution of aluminum atoms for nickel atoms in different crystallographic positions in the 3$d$ sublattice have been considered. An analysis of the band structure has demonstrated that substitutional aluminum impurities lead to the formation of nonmagnetic nickel 3$d$ states and to a significant decrease in the electron density of states at the Fermi level. A comparison of the total energies of the substitutional configurations has revealed that the occupation of the 3$g$ positions by aluminum atoms is more energetically favorable.