The effect of core-valence correlation on transition metal clusters and surfaces : a theoretical study

University dissertation from Stockholm : Stockholm University

Abstract: Ten studies, using the methods of quantum chemistry to study transition metal clusters and surfaces, are presented. The effect of including correlation between the core and valence-electrons are studied, both with an approximative operator and with the core-electrons explicitly correlated.The chemisorption of hydrogen and oxygen on a copper-cluster as a model of the copper-surface are studied. The results are in good agreement with experimental results. For several other copper-containing systems, such as CuH, Cu-2 and CuF, it is shown that it is important to include core-valence correlation effects in order to reach quantitatively correct results.Copper and nickel clusters with up to ten atoms are studied with respect to ionization energies, electron detachment energies and to the geometrical structures of the clusters. For the Nie and Nis clusters, it is shown that an ionization out of the 3d shell is lower in energy than out of the 4s shell.Very large calculations on the scandium atom and dimer are presented. The discrepance between the calculated De of 0.77 eV and the experimental value of ~1.2 eV is discussed. A partition function with several low-lying states for the dimer is presented and its effect on the experimentally determined De is discussed.