Projected Hartree-Fock in a shell-model basis

We implement projected Hartree-Fock in a shell model basis and compare against exact numerical results from full space diagonalization. We consider the accuracy of projected Hartree-Fock for the excited state spectrum in the cases of the $s-d$ and $p-f$ fixed parity shells as well as cases of mixed parity in the $p-sd$ shell. The accuracy of valence proton-neutron number configurations are also considered including even-even, odd-odd, and odd-A.