A First Principles Electronic Structure Study of Quantum Size Effects in (111) Films of delta-Plutonium

TL;DR

This study uses first principles calculations to analyze quantum size effects on surface energies and work functions of ultra-thin delta-Pu (111) films, revealing rapid convergence of surface energy and strong size effects on work function.

Contribution

It provides the first detailed first-principles analysis of quantum size effects in delta-Pu films, including relativistic effects, and compares results with experimental data.

Findings

Surface energy converges rapidly with film thickness.

Work function shows strong quantum size effects.

Predicted surface energy and work function align with recent experiments.

Abstract

First principles linear combinations of Gaussian type orbitals-fitting function (LCGTO-FF) electronic structure calculations are used to study thickness dependencies in the surface energies and work functions of ultra-thin (111) films of fcc delta-Pu, up to five layers thick. The calculations are carried out at both scalar- and fully-relativistic (with and without spin-orbit coupling) levels of approximation. The surface energy is shown to be rapidly convergent, while the work function exhibits a strong quantum size effect for all thicknesses considered. The surface energy and work function of the semi-infinite solid are predicted to be 1.12 J/m^2 and 2.85(+ or -0.20) eV, respectively, for the fully-relativistic case. These results are in substantial disagreement with results from previous electronic structure calculations. The present predictions are in fair agreement with the most recent experimental data for polycrystalline delta-Pu, namely 0.91 J/m^2 and 3.1-3.3 eV, for the surface energy and work function, respectively.