Simple parametrization for low energy octupole modes ofs-dshell nuclei

We demonstrate that the energy eigenvalues of the low energy octupole modes of nuclei in the Z=12–20, N=12–20 region follow a simple pattern which can be observed in a graph of E${(3\mathrm{}}_1^{\mathrm{-}}$) versus $N_{\mathrm{p}+N_{\mathrm{n}}}$, where $N_{\mathrm{p}}$ ($N_{\mathrm{n})}$ is the valence number of protons (neutrons) in the s-d shell. This pattern is discussed in terms of a parametrization for these states which has previously been applied to several regions of spherical and transitional nuclei between atomic masses 60 and 220.