Charge density functional plus U calculation of lacunar spinel GaM4Se (M = Nb, Mo, Ta, and W)

Abstract

Charge density functional plus U calculations are carried out to examine the validity of molecular J(eff) = 1/2 and 3/2 states in lacunar spinel CaM(4)Ses (M = Nb, Mo, Ta, and W). With LDA (spin-unpolarized local density approximation)+U, which has recently been suggested as a more desirable choice than LSDA (local spin density approximation)+U, we examine the band structure in comparison with the previous prediction based on the spin-polarized version of functional and with the prototypical J(eff) = 1/2 material Sr2IrO4. It is found that the previously suggested J(eff) = 1/2 and 3/2 band characters remain valid still in LDA+U calculations while the use of charge-only density causes some minor differences. Our result provides further support for the novel molecular J(eff)( )state in this series of materials, which can hopefully motivate the future exploration toward its verification and the further search for new functionalities. Copyright (C) EPLA, 2019