2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/229469We study the spherical to prolate-deformed shape transition in $^{144-158}$Sm and $^{146-160}$Gd isotopes with modern calculations beyond the mean field with the Gogny D1S force. We compare the results with the shape-phase transition predicted by the collective hamiltonian model and with the experimental data. Our calculations do not support the existence of a first order phase transition in these isotopic chains in the viewpoint of the Bohr hamiltonian neither the interpretation of the nuclei N=90 as critical points.Proceeding of the XIII Conference on Capture Gamma-ray Spectroscopy and Related Topics, Cologne, 2008Nuclear Theorytext