  Using the previously developed model we revisit the problem of the electric
field induced polarization rotation in antiferroelectric crystals of squaric
acid. We test an alternative set of the model parameters, according to which
the dipole moments associated with the H$_2$C$_4$O$_4$ groups are assumed to be
parallel to the diagonals of the $ac$ plane. The $T$-$E$ phase diagrams and the
polarization curves $P(E)$ for the fields directed along the $a$ axis and along
one of the diagonals are considered. Comparison of the theoretical results with
the newly published experimental data confirm the validity of the model. The
calculations reveal no apparent advantage of the new set of the parameters over
the previously used set.
