  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.
