Electronic Structure and Fermi Surface of NpGe₃

Abstract

Fermi surface topology of transuranium compound NpGe₃ is investigated from an itinerant 5f 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 NpGe₃ is sensitive to the lattice constant because of its special shape. A LDA equilibrium lattice constant of NpGe₃ is determined from total-energy minimization as a function of lattice constant under the AuCu₃-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 5f band scheme, though Np-5f electrons are more localized than those of a lighter actinide atom.