The effects of mesoscale confinement in Pu clusters and isolated particles

Calculations of the electronic structure of Pu crystal clusters and isolated particles formed by a finite number of atoms have been performed in terms of the fully relativistic discrete variational (RDV) method, using two types of atomic wave functions incorporated into the RDV code. The density of states results for the central atoms of the finite-size Pu systems as well as the calculated 4f core level energy schemes, for the clusters of different size and structure have been compared to the relevant experimental spectra obtained by synchrotron-radiation-based photoelectron spectroscopy. The robust result of our investigation is the observation of systematic average electronic structure evolution from atomic to bulk behavior through the cluster/nanoparticle regime. The effects of mesoscale confinement established in the present work impose certain limitation for the electronic structure of bulk plutonium and can be useful for the interpretation of Pu photoelectron spectra.