Masses and Quadrupole Deformations of Even-Z Nuclei Within a Triaxial Relativistic Hartree–Bogoliubov Model

This study investigates the masses and quadrupole deformations of even-Z nuclei within the range 8⩽Z⩽104 using the triaxial relativistic Hartree–Bogoliubov model (TRHB) with the PC-PK1 density functional. For odd-mass nuclei, the global minima were determined using the automatic blocking method and their dynamical correlation energies (DCEs) were approximated using the average values of neighboring even–even nuclei calculated from a microscopic, five-dimensional, collective Hamiltonian (5DCH). The mean-field results underestimate the binding energies of most open-shell nuclei, with an initial root–mean–square (rms) deviation of 2.56 MeV for 1223 even-Z nuclei. Incorporating DCEs significantly reduces this deviation to 1.36 MeV. Additionally, the descriptions of two-neutron and one-neutron separation energies are improved, with rms deviations decreasing to 0.75 MeV and 0.65 MeV, respectively. Further refinement through accounting for odd–even differences in DCEs reduces the rms deviations for binding energies and one-neutron separation energies to 1.30 MeV and 0.63 MeV, respectively. Regarding the quadrupole deformations, TRHB calculations reveal spherical shapes near shell and subshell closures, well-deformed shapes at the mid-shell, and rapid shape transitions in medium- and heavy-mass regions. Oblate shapes dominate in regions (Z,N)∼(14,14),(34,36), and (40,60), and the neutron-deficient Pb region, with notable odd–even shape staggering attributed to the blocking effect of the odd nucleon. Triaxial shapes are favored in the mass regions (Z,N)∼(60,76) and (76,116).