A hybrid density functional cluster study of the bulk and surface electronic structures of plutonium monoxide

A hybrid density functional theory with Becke's three-parameter functional and the correlation functional of Lee, Yang and Parr (B3LYP) and relativistic effective core potentials has been applied to investigate the electronic structures of both the bulk and the (1 0 0) surface of plutonium monoxide. The bulk and the surface have been represented by a set of molecular clusters embedded in large arrays of point charges. A large overlap between the Pu 5f bands and O 2p bands and a significant covalent nature in the chemical bonding are found in the monoxide. The highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gaps and the density of states (DOS) of the clusters tend to support the idea that PuO is a semiconductor. The valence bandwidth is found to increase with the cluster size and tends to be saturated. (C) 2001 Elsevier Science B.V. All rights reserved.