Determination of the parameters of a Skyrme type effective interaction using the simulated annealing approach

Abstract

We implement for the first time the simulated annealing method (SAM) to the problem of searching for the global minimum in the hyper-surface of the chi-square function which depends on the values of the parameters of a Skyrme type effective nucleon-nucleon interaction. We undertake a realistic case of fitting the values of the Skyrme parameters to an extensive set of experimental data on the ground state properties of many nuclei ranging from normal to exotic ones. The set of experimental data used in our fitting procedure includes the radii for the valence $1d_{5/2}$ and $1f_{7/2}$ neutron orbits in the $^{17}$O and $^{41}$Ca nuclei, respectively, and the breathing mode energies for several nuclei, in addition to the typically used data on binding energy, charge radii and spin-orbit splitting. We also include in the fit the critical density $ρ_{cr}$ and further constrain the values of the Skyrme parameters by requiring that (i) the quantity $P = 3ρ\frac{dS}{dρ}$, directly related to the slope of the symmetry energy $S$, must be positive for densities up to $3ρ_0$ (ii) the enhancement factor $κ$, associated with the isovector giant dipole resonance, should lie in the range of $0.1 - 0.5$ and (iii) the Landau parameter $G_0^\prime$ is positive at $ρ= ρ_0$. We provide simple but consistent schemes to account for the center of mass corrections to the binding energy and charge radii.