ELECTRONIC-STRUCTURE AND FERMI-SURFACE OF UB12

Based on the itinerant-electron model for the 5f electrons, the energy band structure and the Fermi surface are calculated for the cubic uranium dodecaboride UB12, known to be a paramagnet having the electronic specific heat constant of 20 mJ/K2 mole, by a self-consistent relativistic APW method with the exchange and correlation potential in the local-density approximation. The energy band structure is that of a compensated metal having 0.32 holes/cell and the compensating number of electrons. Both the hole and the electron sheets of the Fermi surface are multiply-connected with open orbits, the direction of which is consistent with the high-field magnetoresistance. By these Fermi surfaces, both the magnitude and the angular dependence of the frequency branches of the de Haas-van Alphen effect observed recently by Onuki et al. can be explained reasonably well.