The electronic spectra of UO2F2, both isolated and hydrated, have been stud
ied using ab initio spin-orbit configuration interaction calculations based
on relativistic effective core potentials. The structures of UO2F2 species
were obtained by the density functional theory method. The initial structu
re has a (nonplanar) C-2v geometry, while adding solvating water molecules
and optimizing the structure UO2F2H2O)(n) give a very stable structure for
n = 4, with D-2 geometry. The ground state and some excited states were stu
died for UO2F2(H2O)(n) using the structures obtained. Electric-dipole trans
ition moments were calculated for UO2F2(H2O)(4)Spin-orbit and equatorial -
ligand (F-, H2O) interactions compete in determining the splittings of the
known (3)Deltag state of the uranyl ion, particularly the 3 Delta (1g) lumi
nescent state.