NOTORIOUS DISCREPANCIES IN CRYSTAL-FIELD ANALYSES ELIMINATED BY CONFIGURATION-INTERACTION

Some conspicuous discrepancies between experimental and calculated ene rgy levels in the crystal held analysis of actinide (5f(2)) electronic spectra are eliminated if one includes in the interaction matrix the participation of the excited configuration in addition to the ground c onfiguration. This was recently demonstrated in the case of the tetrav alent uranium U4+ in the cubic centrosymmetric sites of elpasolithe co mpounds (M.D. Faucher, O.K. Moune, D. Garcia and P. Tanner, Phys. Rev. B, 53 (1996) 9501). The present work is a step towards the generaliza tion of the proposition. It is shown that it is also true for the 4f(3 ) configuration of Nd3+ in non-centrosymmetric sites. Indeed, the noto rious discrepancy between experimental and calculated sublevels of the H-2(2)(11/2) group at 15000 cm(-1) is eliminated by configuration int eraction with the excited 4f(2)6p(1) configuration. The experimental c ase of Nd2O2S is quoted as an example, but the demonstration is valid for all neodymium compounds.