Fayans Functional. Constraints from Equations of State

A variational analysis of the Fayans energy-density functional is performed with allowance for the earlier unused isovector parameters @ in the volume part of the functional. The quality of the previous fit to nuclear densities, masses of nuclei, single-particle levels, and charge radii remains unchanged under the additional condition of description of the giant-dipole-resonance energy in the @Pb nucleus. The effect of variations in the isovector parameter @ on the equations of state for infinite symmetric nuclear matter and pure neutron matter is determined. The density dependence of the symmetry energy @ and of its derivative @ is studied. For the parameter @, a range is established that is consistent with the estimated values of the symmetry energy @ and its derivative @ at the equilibrium density @, which are parameters of the equation of state for symmetric nuclear matter. These values were obtained earlier from a simultaneous analysis of the values of the ‘‘neutron skin’’ @ of @Pb and @Ca nuclei from the PREX-II and CREX experiments, from the results of ab initio calculations of equations of state and ground-state properties of nuclei, and from astrophysical observations and data on the discovery of gravitational waves from the merger of binary neutron stars by the LIGO-Virgo Collaboration in 2017.