We have performed two kinds of non-linear fitting procedures to the single-particle energies in the $sdgh$ major shell to obtain better shell model results. The low-lying energy eigenvalues of the light Sn isotopes with $A=103-110$ in the $sdgh$-shell are calculated in the framework of the nuclear shell model by using CD-Bonn two-body effective nucleon-nucleon interaction. The obtained energy eigenvalues are fitted to the corresponding experimental values by using two different non-linear fitting procedures, i.e., downhill simplex method and clonal selection method. The unknown single-particle energies of the states $2s_{ 1/2}$, $1d_{ 3/2}$, and $0h_{ 11/2}$ are used in the fitting methods to obtain better spectra of the $^{ 104,106,108,110}$Sn isotopes. We compare the energy spectra of the $^{ 104,106,108,110}$Sn and $^{ 103,105,107,109}$Sn isotopes with/without a nonlinear fit to the experimental results.
Categories: nucl-th