Calculations on Autoionization of theP524°State ofHe−

The lifetime against autoionization of the ${}_{}{}^4{}_{}{}^{}P_{\frac{5}{2}}^{}{}_{}{}^{}°$ state of ${\mathrm{He}}^{-}$ is calculated using an accurate description of the initial- and final-state wave functions. In these calculations the initial ${}_{}{}^4{}_{}{}^{}P_{\frac{5}{2}}^{}{}_{}{}^{}°$ state is represented by a variational wave function consisting of several angular configurations. The final ${}_{}{}^4{}_{}{}^{}F_{\frac{5}{2}}^{}{}_{}{}^{}°$ continuum state is obtained by polarized-orbital theory. A lifetime of 4.55×${10}^{-4\mathrm{}}$ sec is predicted which is in good agreement with the most recent experimental measurement.