Effect of Mott-Hubbard correlations on the electronic structure and structural stability of uranium dioxide

The influence of Mott-Hubbard electron-electron correlations on the electronic structure and structural stability of uranium dioxide (UO2) has been analysed using the local spin-density approximation (LSDA) + U approach. We have found that the inclusion of a term describing the Hubbard on-site repulsion between 5f electrons results in a dramatic improvement in the description of the equilibrium electronic and magnetic structure of UO2 for which conventional LSDA calculations incorrectly predict a non-magnetic metallic ground state. We have found that the presence of electron-electron correlations in the 5f band modifies the character of chemical bonding in the material, leading to a Heitler-London type of hybridization between the 5f orbitals and giving rise to a larger value of the equilibrium lattice constant in better agreement with experimental observations.