Lithium quadrupole properties and Van der Waals constants using pseudo-state techniques

Pseudo-spectral techniques are used to evaluate the moments of the quadrupole oscillator strength distribution for the ground-state Li atom and the dipole-quadrupole Van der Waals constants for the ground-state Li-Li, Li-He and Li-H interactions. The analysis of the pseudo-state data allows an error to be assigned to each calculated Li quadrupole property and Van der Waals constant. The pseudo-state approach also allows a quantitative estimate of the contributions of the Li atom quadrupole resonance, principal series and inner shell transitions to each Li atom quadrupole properly. The convergence of the sum over states expressions for the quadrupole properties of Li is quite different than for the corresponding dipole properties.