Ab initio computations from ${}^{78}$Ni towards ${}^{70}$Ca along neutron number $N=50$

Abstract

We present coupled-cluster computations of nuclei with neutron number $N=50$ "south" of ${}^{78}$Ni using nucleon-nucleon and three-nucleon forces from chiral effective field theory. We find an erosion of the magic number $N=50$ toward ${}^{70}$Ca manifesting itself by an onset of deformation and increased complexity in the ground states. For ${}^{78}$Ni, we predict a low-lying rotational band consistent with recent data, which up until now has been a challenge for ab initio nuclear models. Ground states are deformed in ${}^{76}$Fe, ${}^{74}$Cr, and ${}^{72}$Ti, although the spherical states are too close in energy to unambiguously identify the shape of the ground state within the uncertainty estimates. In ${}^{70}$Ca, the potential energy landscape from quadrupole-constrained Hartree-Fock computations flattens, and the deformation becomes less rigid. We also compute the low-lying spectra and $B(E2)$ values for these neutron-rich $N=50$ nuclei.

10 pages, 6 figures, supplementary material

References in corpus (8)

• Improved nuclear matter calculations from chiral low-momentum interactions
• Evolution of shell structure in neutron-rich calcium isotopes
• A nucleus-dependent valence-space approach to nuclear structure
• Coupled-cluster theory for three-body Hamiltonians
• ${}^{78}$Ni revealed as a doubly magic stronghold against nuclear deformation
• Symmetry broken and restored coupled-cluster theory I. Rotational symmetry and angular momentum
• In-medium similarity renormalization group with three-body operators
• Emergent symplectic symmetry in atomic nuclei: Ab initio symmetry-adapted no-core shell model