Defect structure of nonstoichiometric plutonium oxide

The first-principles plane-wave pseudopotential calculations have been done to evaluate the electronic structures, structural optimization, and formation energy of point defect in plutonium dioxide. The electron density of state and the charge density near the oxygen vacancy have been analyzed. The calculation results show that only the nearest neighbor plutonium atoms are affected by the oxygen vacancy. This agrees with the following picture used in the classical defect chemistry, that is, the oxygen has two electrons provide by plutonium, which are left behind when an oxygen atom is leaving lattice position. These two electrons are localized on two plutonium atoms, turning Pu⁺⁴ into Pu⁺³.