CI calculations for ground and the lowest core-excited states of Li and Li−

Abstract

Large scale, accurate non-relativistic configuration interaction (CI) calculations for the ground and core excited states of Li (2S, 4P° and 4P) and Li− (1S, 5P and 5S°) corrected for relativistic and mass polarization effects. Priori selected CI and CI by parts techniques are implemented to approximate both the large scale wavefunction and the solution of large CI eigenvalue problem respectively. Systematic studies of energy and electron affinity convergence with respect to CI excitation level are reported. The calculated value of electron affinity of the ground 1S state is 618.05(5) meV in excellent agreement with experiment. Calculations on excited states reveal more accurate values of the positions of 5P and 5S° states of Li−, lying 505.86(5) meV and 291.20(5) meV below 4P° and 4P states respectively of Li. Transition energies and wavelength of the electric dipole decay 4P → 4P° of Li and 5S° → 5P of Li−, show reasonably good agreement with available theoretical and experimental data.