In this work, an experimental and theoretical studies of critical scattering for the PbZr0.976Ti 0.024O3 (PZT2.4) compound in the vicinity of the Brillouin zone center have been carried out taking into account the mode coupling. The scattering measurements were carried out at the European Synchrotron Radiation Facility (ESRF). One-dimensional profiles of the scattering intensity dependence on the wave vector were obtained using specially developed programs. The Last model was used for the optical soft mode in the Brillouin zone center. The frequencies and polarization vectors of the renormalized modes were determined by quantitative analysis of the scattering profile for the soft direction [1 0 1]. Good agreement between the calculated results of the model and the experimental data was achieved. The polarization vector’s change of the lowest transverse acoustic mode was traced as a function of the reduced wave vector.