Possibility of a δ-like surface for α-Pu: Theory

Abstract

The electronic structure of a Pu square-mesh monolayer, a five-layer Pu (100)-orientation slab cut from a fcc lattice, and bulk fcc Pu have been calculated. For the monolayer calculation we allowed for spin and orbital polarization; and at all densities, from below the \ensuremath{\delta} to above the \ensuremath{\alpha} density, we found large spin and orbital moments. The equilibrium lattice constant for the monolayer was found to be expanded by about \ensuremath{\sim}7%, compared to our bulk result (which is contracted \ensuremath{\sim}7% from experiment). At both the theoretical and experimental \ensuremath{\alpha} densities we found the five-layer slab to spin polarize, with spin moments close to that of the monolayer. Together with the experimental grazing-incidence photoemission, our results provide support for the existence of a small-moment \ensuremath{\delta}-like surface state for the surface behavior of \ensuremath{\alpha} plutonium.