Atomic Term Energies for Atoms and Ions with 11 TO 28 Electrons

Calculations of term energies based on Z-expansion theory are extended to N-electron atoms and ions with 11 < N < 28. Results of these calculations indicate that the theory is applicable to complex atoms, including the transition elements. Of particular interest is the fact that the first-order perturbations demanded by the Z-expansion account for discrepancies formerly allowed for by the addition of an empirical orbital interaction to the Hamiltonian. The L-dependence of this empirical correction corresponds in the present calculation to a tendency for the number of interactions within a complex to increase with decreasing L, even though individual interactions do not depend systematically on L. The calculation of the electrostatic perturbations was done in three steps; (i) antisymmetric wave functions diagonal in S, M8, L, and ML were generated by means of projection operators; (ii) matrix elements were calculated in this representation; (iii) the matrices were diagonalized.