96-12E

On the basis of proposed earlier model, the effects of applied hydrostatic pressure on the physical properties of DKDP type crystals are studied. Within the cluster approximation for proton model the dielectric, thermal and elastic characteristics of considered crystals are calculated. Detailed numerical analysis of obtained results is performed. It is shown that under the proper choice of the theory parameters a satisfactory description of experimental results for the pressure dependences of spontaneous polarization, static dielectric permittivities and transition temperature is obtained. To explain the experimentally determined behavior of elastic constants the anharmonic effects must be taken into account.