Periodic trends governing the interactions between impurity atoms [H–Ar] and α-U

Abstract

The binding energies, geometries, charges and electronic structures of a series of impurity atoms [H–Ar] interacting with the α-U lattice in various configurations were assessed by means of density functional theory calculations. Periodic trends governing the binding energy were highlighted and related to the electronic properties of the impurity atoms, with some consideration given to the band-structure of α-U. The strongest bound impurity atoms include [C, N, O] and [Si, P, S]. The general trends in the binding energy can be reproduced by a simple parameterisation in terms of the electronegativity (charge-transfer) and covalent radius (elasticity theory) of the impurity atom. The strongest bound atoms deviate from this model, due to their ability to bind with an optimum mixture of covalency and ionicity. This last point is evidenced by the partial overlap of the impurity atom p-band with the hybrid d–/f-band of α-U. It is expected that the trends and general behaviour reported in this work can be extended to the interactions of impurity atoms with other metallic systems.

Keywords:

• uranium
• absorption
• impurity
• thermodynamics
• ab-initio
• periodic trends

Acknowledgements

The author gratefully acknowledges helpful discussions with Michael Francis at the University of Virginia and Dr Scott Lillard at Los Alamos National Laboratory. The author also thanks Saryu Jindal and Dr Chao Jiang (Los Alamos National Laboratory), as well as anonymous reviewers, for careful readings of the manuscript and their recommendations. Gratitude is also expressed towards the Seaborg Post-Doctoral Program at Los Alamos National Laboratory for funding this work. The Los Alamos National Laboratory is operated by Los Alamos National Security LLC for the National Nuclear Security Administration of the US Department of Energy under contract DE-AC52-06NA25396.