The Low Even Configurations of Hf ii

The experimental energy levels and $g$ values of the low even configurations $d{s}^2$, $d^{2}s$, and $d^3$ of Hf ii, are compared with the theoretical formulas for intermediate coupling with configuration interaction. The energy levels are in good agreement, while the mean error is less than 0.7 percent of the configuration width; the agreement between calculated and observed $g$ values is satisfactory.