  The two-phase (space groups $Cc$ and $Cm$) structural model recently proposed
for the modeling of the neutron powder diffaction pattern collected on
Pb(Zr$_x$Ti$_{1-x}$)O$_3$ (PZT) sample with $x\approx 0.52$ [R. Ranjan, A. K.
Singh, Ragini, and D. Pandey. \textit{Phys. Rev. B} \textbf{71}, 092101 (2005)]
is shown to neglect the $hkl$ dependent (anisotropic) line broadening. The most
serious problem with this model is that it assigns octahedral tilts to a wrong
phase. Instead of correctly taking the anisotropic line broadening into
account, this model used low symmetry phases to minimize the residuals during
Rietveld refinement. The essential features of a model taking the $hkl$
dependent line broadening into account are summarized. It has already been
reported that once the anisotropic line broadening, revealed by high resolution
neutron powder diffraction instrument, is correctly taken into account the
model with $R3c$ and $Cm$ space group symmetries describes all Bragg peaks and
their intensities well [J. Frantti, S. Eriksson, S. Hull, V. Lantto, H.
Rundl\"of, and M. Kakihana. \textit{J. Phys.: Condens. Matter} \textbf{15},
6031 (2003).]. It was further shown that the $Cm+R3c$ model is consistent with
the structural features observed at other compositions and temperatures, which
is particularly important in the vicinity of the phase boundary. Also problems
related to sample preparation and data collection are pointed out.
