IONIZATION-POTENTIALS AND ELECTRON-AFFINITIES OF CU, AG, AND AU - ELECTRON CORRELATION AND RELATIVISTIC EFFECTS

The electron correlation and relativistic effects on ionization potent ials and electron affinities of Cu, Ag, and Au are investigated in the framework of the coupled cluster method and different 1-component app roximations to the relativistic Dirac-Coulomb Hamiltonian. The first-o rder perturbation approach based on the mass-velocity and Darwin terms is found to be sufficiently accurate for Cu and Ag while it fails for Au. The spin-averaged Douglas-Kroll no-pair method gives excellent re sults for the studied atomic properties. The ionization potentials obt ained within this method and the coupled cluster scheme for the electr on correlation effects are 7.733(7.735) eV for Cu, 7.461(7.575) eV for Ag, and 9.123(9.225) eV for Au (experimental values given in parenthe ses). The calculated (experimental) electron affinity results for Cu, Ag, and Au are 1.236(1.226), 1.254(1.303), and 2.229(2.309) eV, respec tively. There is a marked relativistic effect on both the ionization p otential and electron affinity of Ag which sharply increases for Au wh ile Cu exhibits only a little relativistic character. A similar patter n of relativistic effects is also observed for electric dipole polariz abilities of the coinage metal atoms and their ions. The coupled clust er dipole polarizabilities of the coinage metal atoms calculated in th is article in the Douglas-Kroll no-pair formalism (Cu: 46.50 au; Ag: 5 2.46 an; Au: 36.06 an) are compared with our earlier data for their si ngly positive and singly negative ions. (C) 1997 John Wiley & Sons, In c.