Quantum size effects in α-plutonium (020) surface layers

We present a systematic first principles density functional theory (DFT) based study of the (020) surface of α-plutonium using the projector-augmented-wave formalism as implemented in the Vienna Ab Initio Simulation Package (VASP). The surface was modeled by a periodic slab geometry comprised of anti-ferromagnetic atomic layers, with a thickness of up to ten atomic layers. The total and cohesive energies indicate a monotonically decreasing and increasing slope to the bulk values, respectively. The surface energies, in contrast to the work functions, exhibit a significant oscillatory pattern indicating persistent quantum size effects and possible magnetic frustration as well as other effects. The 5f electron density of states indicates progressive delocalization with increasing slab thickness.