Ground State Electron Configuration of Element 111

The low-lying electronic states of element 111 are investigated by the relativistic coupled-cluster method based on the Dirac-Coulomb-Breit Hamiltonian. A large basis set ($26s21 p 16d9f7g5h$) of Gaussian-type orbitals is used. In contrast to the lighter group 11 elements, the ground state of the atom is ${6d}^9{7s}^2{}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{}$; the ${}_{}{}^2{}_{}{}^{}D_{\frac{3}{2}}^{}{}_{}{}^{}$ state is higher by 2.69 eV, and the ${6d}^{10}7s{}_{}{}^2{}_{}{}^{}S$ lies 2.95 eV above the ${}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{}$. The reversal is ascribed to relativistic effects; without them, the ${}_{}{}^2{}_{}{}^{}S$ energy is 5.43 eV below the ${}_{}{}^2{}_{}{}^{}D$. The calculated electron affinity of the atom is 1.56 eV, and its ionization potential is 10.6 eV.