07-17U

The proton formalism based on the de Gennes model is applied for description of thermodynamic and dielectric properties of CsH$_2$PO$_4$ ferroelectrics. The short-range and long-range interactions are taken into account within the two-particle cluster approximation and the mean field approximation, respectively. The calculations of the physical characteristics of CsH$_2$PO$_4$ are carried out with and without proton tunneling on hydrogen bounds. It is shown that more adequate description of experimental data within the applied theoretical approach is obtainable at the zero tunneling parameter.