Comments on the ferroelectric "soft mode" in orthorhombic KNbO3

The assignment of a Raman feature at 56 ${\mathrm{cm}}^{-1\mathrm{}}$ in orthorhombic KNb${\mathrm{O}}_3$ as the soft mode by Bozinis and Hurrell is shown to be incompatible with other data. This feature actually arises from the one-phonon density of states and is evidence of the order-disorder character of ferroelectricity in KNb${\mathrm{O}}_3$.