CORRELATED BAND MAGNETISM OF CERIUM AND ACTINIDE MATERIALS

We discuss (1) the effects to be expected by the introduction into the electronic structure of locally-based two-electron correlations betwe en the f electrons and bonding electrons of p and d atomic origin cent ered off-site as well as f-f correlations, (2) the expected observable consequences of these two-electron correlations, and (3) how to perfo rm electronic structure calculations including the two-electron correl ations. We first review certain general features of the physics associ ated with capturing the dual energetically localized-delocalized natur e of the f electron spectral density; and review model calculations in volving a single on-site f electron and a single ligand p/d electron o f off-site parentage which lead to the possibility of a narrow singlet and triplet (magnetic) band picture explaining heavy fermion phenomen ology. We then show that the same singlet/magnetic state picture arise s when we include two-electron f-l and f-f correlations for actinides, which have atomic f(n) configurations with n>1; and we describe a pra ctical electronic structure scheme for real materials based on a seque nce in which a conventional one-electron linearized combination of muf fin-tin orbitals (LMTO) LDA+U calculation is followed by a calculation for the lattice with a helium like two-electron Hamiltonian at the f atom sites, i.e., two-electron atoms where initially for the core two electrons worth of charge are removed from the LMTO f-site atom. This procedure will reconstruct the LMTO bands to include two-electron text uring. (C) 1997 American Institute of Physics.