AB-INITIO CI CALCULATION OF K-SHELL ABSORPTION-SPECTRA IN TRANSITION-METAL COMPOUNDS

The metal 1s excitation spectra of several organometallic compounds have been calculated at the ab initio 1h-1p CI level, providing for an adequate treatment of relaxation and an accurate choice of the basis set. The results are discussed and compared with our previous theoretical results relative to the 2p metal edge for the same systems. The 1s spectra, probing the metal 4p content of the excited states, can identify the final levels complementary to those determined by the metal 2p --> 3d excitations. A complete pattern of the low-lying virtual levels of a particular system can be obtained merging the results relative to the two metal edge spectra (1s and 2p) allowing a detailed discussion on the character of the metal-ligand interaction. The 1s spectra are found to be sensitive to the nature of the ligands and the bonding situation and not dependent on the change of metal atom in series with the same kind of ligands.