ELECTRONIC-STRUCTURE AND 5F-6D ENERGY-GAP OF TRIVALENT ACTINIDES IN ANO(8)(13-), ANCL(6)(3-) AND ANF(8)(5-) CLUSTERS USING DV-X-ALPHA METHOD

Relativistic self-consistent calculations using the Dirac-Slater discr ete variational method (DVM) have been carried out in order to obtain the electronic structure of AnO(8)(13-), AnCl(6)(3-) and AnF(8)(5-) cl usters (An= U3+, Am3+, and Cm3+). From the states compositions, the de gree of An (5f)-ligand (np) covalency is discussed. From the absorptio n and excitation spectra of compounds such as ThO2, Cs2NaYCl6, and LiY F4 doped with Am3+, Cm3+ or U3+, intense broad bands observed in the U V region are attributed to 5f-6d transitions. The first maximum of the se bands is compared to the energy difference between the last occupie d 5f orbital and the first unoccupied 6d orbital in the ground state e lectronic structure of the clusters.