TRANSITION ENERGIES OF MERCURY AND EKAMERCURY (ELEMENT-112) BY THE RELATIVISTIC COUPLED-CLUSTER METHOD

The relativistic coupled-cluster method is used to calculate ionization potentials and excitation energies of Hg and element 112, as well as their mono- and dications. Large basis sets are used, with l up to 5, the Dirac-Fock or Dirac-Fock-Breit orbitals found, and the external 34 electrons of each atom are correlated by the coupled-cluster method with single and double excitations. Very good agreement with experiment is obtained for the Hg transition energies, with the exception of the high (>12 eV) excitation energies of the dication. As in the case of element 111 [Eliav et al., Phys. Rev. Lett. 73, 3203 (1994)], relativistic stabilization of the 7s orbital leads to the ground state of 112(+) being 6d(9)7s(2), rather than the d(10)s ground states of the lighter group 12 elements. The 112(2+) ion shows very strong mixing of the d(8)s(2), d(9)s, and d(10) configurations. The lowest state of the dication is 6d(8)7s(2) J=4, With a very close (0.05 eV) J=2 state with strong d(8)s(2) and d(9)s mixing. No bound states were found for the anions of the two atoms.