  The nuclear charge radius plays a vital role in determining the equation of
state of isospin asymmetric nuclear matter.
  Based on the correlation between the differences in charge radii of
mirror-partner nuclei and the slope parameter ($L$) of symmetry energy at the
nuclear saturation density, an analysis of the calibrated slope parameter $L$
was performed in finite nuclei. In this study, relativistic and
non-relativistic energy density functionals were employed to constrain the
nuclear symmetry energy through the available databases of the mirror-pair
nuclei $^{36}$Ca-$^{36}$S, $^{38}$Ca-$^{38}$Ar, and $^{54}$Ni-$^{54}$Fe. The
deduced nuclear symmetry energy was located in the range 29.89-31.85 MeV, and
$L$ of the symmetry energy essentially covered the range 22.50-51.55 MeV at the
saturation density. Moreover, the extracted $L_s$ at the sensitivity density
$\rho_{s}=0.10~\mathrm{fm}^{-3}$ was located in the interval range 30.52-39.76
MeV.
