POLARIZED BASIS-SETS FOR HIGH-LEVEL-CORRELATED CALCULATIONS OF MOLECULAR ELECTRIC PROPERTIES .7. ELEMENTS OF THE GROUP IB - CU, AG, AU

The first-order polarized basis sets PolMe are generated for elements (Me = Cu, Ag, Au) of group Ib of the periodic table by using the basis set polarization method developed in earlier papers. The performance of these basis sets is extensively tested in calculations of atomic di pole polarizabilities with particular attention given to the evaluatio n of the electron correlation and relativistic contributions. The exte nsion by the g-type polarization functions (PolMe-g sets) is devised f or use in accurate calculations of atomic and molecular electric prope rties. The (negative) electron correlation contribution to dipole pola rizabilities of all elements of group Ib, as calculated at the level o f the spin adapted coupled cluster method with single and double excit ations and non-iterative corrections for the contribution of the T-3 c lusters (SA CCSD(T)), remains at the same level relative to the ROHF d ata. The pure relativistic correction to the ROHF results, evaluated w ithin the quasirelativistic approximation involving the mass-velocity and Darwin corrections, is negative and rapidly increases with increas e of the nuclear charge. Its large negative value is, for heavier syst ems, partly compensated by a positive contribution from the mixed rela tivistic-correlation terms. Our relativistically corrected SA CCSD(T) calculations predict the following values of the dipole polarizability in the coinage metal series: 46, 51, and 29 a.u., for Cu, Ag, and Au. The present results for Cu and Ag agree well with recent pseudopotent ial calculations by Schwerdtfeger and Bowmaker. However, for Au our re sult is by about 6 a.u. lower than that obtained by using 19-electron relativistic potentials. Several possible reasons for this discrepancy are discussed. The PolMe and PolMe-g basis sets are also used to calc ulate electric dipole polarizabilities of the singly positive ions of group Ib elements. The results obtained in the quasirelativistic CCSD( T) approximation are 6.6, 9.2, and 11.8 a.u. for Cu+, Ag+, and Au+, re spectively. These values follow the pattern expected for the series of ions whose polarizability is dominated by the next-to-valence d shell .