Abstract
The cohesive properties of some actinide metals (thorium, protoactinium and uranium), and of their oxides ThO2 and UO2, were studied by means of the linear muffin-tin orbital method in the atomic sphere approximation. 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 α-U structure. More specifically, the experimental cohesive properties of UO2 and ThO2 are particularly well reproduced. This leads us to propose, from ab-initio calculations, an estimation of the formation energy of oxygen vacancies in UO2.