[Submitted on 8 Apr 2021]
Benchmarking projected Hartree-Fock as an approximation
Stephanie M. Lauber🇺🇸 · Hayden C. Frye🇺🇸 · Calvin W. Johnson🇺🇸
We benchmark angular-momentum projected{-after-variation} Hartree-Fock calculations as an approximation to full configuration-interaction results in a shell model basis. For such a simple approximation we find reasonably good agreement between excitation spectra, including for many odd- and odd-odd nuclides. We frequently find shape coexistence, in the form of multiple Hartree-Fock minima; {mixing in shape coexistence, the first step beyond single-reference projected Hartree-Fock}, demonstrably improves the spectrum in the - and -shells. The complex spectra of germanium isotopes present a challenge: for even the spectra are only moderately good and those of odd bear little resemblance to the configuration-interaction results. Despite this failure we are able to broadly reproduce the odd-even staggering of ground state binding energies, save for germanium isotopes with . To illustrate potential applications, we compute the spectrum of the recently measured dripline nuclide Mg. All in all, projected Hartree-Fock often provides a better description of low-lying nuclear spectra than one might expect. Key to this is the use of gradient descent and unrestricted shapes.
- Comments:
- 21 pages, 11 figures, 2 tables
- Subjects:
- Nuclear Theory (nucl-th)
- arXiv:
- 2104.03455 [pdf]