COHESIVE PROPERTIES OF UO2

The cohesive properties of some actinide metals (thorium, protoactiniu m and uranium), and of their oxides ThO2 and UO2, were studied by mean s of the linear muffin-tin orbital method in the atomic sphere approxi mation. This method gives accurate predictions of the stability of the close-packed structures, but it is found to be less accurate for the most open structure: the alpha-U structure. More specifically, the exp erimental cohesive properties of UO2 and ThO2 are particularly well re produced. This leads us to propose, from ab-initio calculations, an es timation of the formation energy of oxygen vacancies in UO2.