The geometrical and electronic structures of UO₂^2＋ and PuO₂^2＋ have been studied by means of density functional theory (DFT). The calculated results are in fairly good agreement with experimental ones, showing that DFT method can also give reliable results for the calculation of the compounds containing heavy atoms. The fully optimized geometrical structure, Mulliken population and the binding energy between UO₂^2＋ (PuO₂^2＋) and H₂O in UO₂^2＋•nH₂O (PuO₂^2＋•nH₂O) have also been studied. The calculated results show that UO₂^2＋•5H₂O and PuO₂^2＋•5H₂O are the most stable complexes in the series of hydrated ions UO₂^2＋•nH₂O and PuO₂^2＋•nH₂O.

Key words: density functional theory, Mulliken population, binding energy