Electronic Structure and Fermi Surface of NpGe3

Abstract

Fermi surface topology of transuranium compound NpGe 3 is investigated from an itinerant 5 f picture with a relativistic band calculation in a local-density approximation (LDA), thereby analyzing the frequency branches observed by the de Haas–van Alphen (dHvA) effect. The Fermi surface volume of NpGe 3 is sensitive to the lattice constant because of its special shape. A LDA equilibrium lattice constant of NpGe 3 is determined from total-energy minimization as a function of lattice constant under the AuCu 3 -type crystal structure. The Fermi surface obtained at the LDA equilibrium can explain precisely the origin of all the dHvA frequency branches like the familiar Fermi surface of Cu. This suggests that the fermiology of Np compounds should progress on the 5 f band scheme, though Np-5 f electrons are more localized than those of a lighter actinide atom.