Multipoles in δ-Pu

We propose a multipole scenario to understand the absence of magnetism in δ-Pu on the basis of a microscopic model constructed from a j-j coupling scheme. In order to determine the multipole state, we employ a concept of the optimization of multipole susceptibility. By using an exact diagonalization technique for 4-site fcc lattice, we depict the phase diagram, including the states characterized by quadrupole and octupole fluctuations. We discuss the region in our phase diagram with possible relevance to the actual situation for δ-Pu.