Please find below three refs about the quantum chemistry of your ion, but the first screening has shown that there have not data for the potential energies. may be somewhere in the cited reference would have...
1. Ab initio calculations for some oxo-anions of chlorine, bromine and iodine, Christoph Oberle, Hans H. Eysel, Journal of Molecular Structure: THEOCHEM, Volume 280, Issue 1, 11 March 1993, Pages 107–115
2. The Journal of Chemical Physics, Volume 70, Issue 9, 1979, Pages 4194-4198, Vibrations and force constants of the hexagonal lithium iodate crystal, Crettez, J., Misset, J., Coquet, E.
3. The electronic structure of ClO−3, BrO−3 and IO−3: an SCF—Xα study, B.El-Issa, A. Hinchliffe, Journal of Molecular Structure, Volume 67, 1980, Pages 317–321