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 6d⁹7s²²D5/2; the ²D3/2 state is higher by 2.69 eV, and the 6d¹⁰7s²S lies 2.95 eV above the ²D5/2. The reversal is ascribed to relativistic effects; without them, the ²S energy is 5.43 eV below the ²D. The calculated electron affinity of the atom is 1.56 eV, and its ionization potential is 10.6 eV.