  A fully consistent relativistic random phase approximation is applied to
study the systematic behavior of the isovector giant dipole resonance of nuclei
along the $\beta$-stability line in order to test the effective Lagrangians
recently developed. The centroid energies of response functions of the
isovector giant dipole resonance for stable nuclei are compared with the
corresponding experimental data and the good agreement is obtained. It is found
that the effective Lagrangian with an appropriate nuclear symmetry energy,
which can well describe the ground state properties of nuclei, could also
reproduce the isovector giant dipole resonance of nuclei along the
$\beta$-stability line.
