Mean field calculation of Ne, Mg and Si nuclei at N=20 with the separable monopole interaction

A new model has been developed to study nuclei using many-body perturbation theory with a density dependent separable monopole nucleon-nucleon interaction (SMO) [Phys. Rev. C 63 (2001) 054309; P.D. Stevenson, D.Ph. Thesis, Oxford 1999; Phys. Rev. C 65 (2002) 064312]. The model is in the zeroth order an alternative to mean-field models based on more conventional effective nucleon-nucleon interactions (e.g., Skyrme, Gogny). Results on shapes and related ground state observables are reported for even-even Ne, Mg, and Si nuclei with N similar to 20. The model predicts the weakening of the expected N = 20 shell closure in Ne isotopes and its disappearance in Mg nuclei in full agreement with experimental results. (C) 2002 Elsevier Science B.V. All rights reserved.