  The deformation evolution of giant dipole resonance (GDR), in the chains of
Sm and Nd isotopes, are investigated in the framework of an extended quantum
molecular dynamics (EQMD) model. The mass number dependence of resonance peak
position $(E_{m})$ in the major and minor axis directions of deformed nuclei as
well as the difference $\Delta E_{m}$ between them are described in detail. The
correlation between the splitting ($\Delta E_{m} /\bar{E}_m $) of the GDR
spectra and the deformation($ \beta_{2}$) is further studied. The results
confirm that $\Delta E_{m} /\bar{E}_m $ is proportional to $ \beta_{2}$. By
comparing the calculation with the experimental data on photon absorption cross
section $\sigma_{\gamma}$, it shows that the EQMD model can quite well
reproduce the shape of GDR spectra from spherical to prolate shape. The GDR
shapes in $^{134}$Sm, $^{136}$Sm, $^{138}$Sm, $^{130}$Nd, $^{132}$Nd and
$^{134}$Nd are also predicted. In addition, the symmetry energy coefficient
$(E_{sym})$ dependence of GDR spectra of $^{150}$Nd is also discussed. It is
found that the calculated GDR spectrum in the EQMD model is perfectly
consistent with the experimental results when $E_{sym}$ equals to 32 MeV.
