Calculation of the parity mixing between the lowest0−,0 and0+,1 levels inF18

The parity mixing in the 1040, 1080 keV doublet ($J,T=0^{+},1\mathrm{} \mathrm{and} 0^{-},0, \mathrm{respectively}$) of ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ has been calculated in the frame of the spherical shell model with different residual interactions. In this case only the isovector part of the parity violating potential is effective, and only the dominating one-pion-exchange term has been considered. The shell model space includes the $0p_{\frac{1}{2}}$, $0d_{\frac{5}{2}}$, and $1s_{\frac{1}{2}}$ orbits. The influence of a further truncation of the model space has also been investigated. The results appear not to depend drastically on the choice of the residual interaction among those reported in the literature. The same conclusion appears to hold for the matrix element of the one-pion-exchange potential between the ${1/2}^{-}$ and ${1/2}^{+}$ levels at 2788 and 2796 keV in ${}_{}{}^{21}{}_{}{}^{}\mathrm{Ne}$.