Fayans Functional. Constraints from Equations of State

variational analysis of the Fayans energy-density functional is performed with allowance for the earlier unused isovector parameters h_2^- 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 ^208 Pb nucleus. The effect of variations in the isovector parameter h_2^- on the equations of state for infinite symmetric nuclear matter and pure neutron matter is determined. The density dependence of the symmetry energy S(ρ) and of its derivative L(ρ) is studied. For the parameter h_2^- , a range is established that is consistent with the estimated values of the symmetry energy J=S(ρ_0) and its derivative L_0=L(ρ_0) at the equilibrium density ρ_0 , 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’’ Δ Rnp of ^208 Pb and ^48 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.