Configuration mixing of angular-momentum-projected triaxial relativistic mean-field wave functions. II. Microscopic analysis of low-lying states in magnesium isotopes

The recently developed structure model that uses the generator coordinate method to perform configuration mixing of angular-momentum projected wave functions, generated by constrained self-consistent relativistic mean-field calculations for triaxial shapes (3DAMP$+$GCM), is applied in a systematic study of ground states and low-energy collective states in the even-even magnesium isotopes ${}^{20--40}$Mg. Results obtained using a relativistic point-coupling nucleon-nucleon effective interaction in the particle-hole channel and a density-independent $\ensuremath{\delta}$ interaction in the pairing channel are compared to data and with previous axial 1DAMP$+$GCM calculations, both with a relativistic density functional and the nonrelativistic Gogny force. The effects of the inclusion of triaxial degrees of freedom on the low-energy spectra and $E2$ transitions of magnesium isotopes are examined.