Ground State Electron Configuration of Element 111

Abstract

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.