Investigation on the symmetry and the order parameter of the displacive antiferroelectric phase transition

The shortage of the order parameter of the antiferroelectric phase in the previous reference is pointed out. An axial vector R = Sigma(i) q(i)r(i) x Delta r(i)/V was proposed as the order parameter of the displacive antiferroelectric phase. This vector is of the symmetry groupC(infinity i). Using R as the order parameter, we reinvestigated the antiferroelectric model of Kittle type. We find that the vector can adequately reflect the symmetry change of the paraelectric-antiferroelectric phase transition by using Curie principle.