The structural parameters, the elastic and dielectric constants, and the vibrational spectrum of KCuF3 have been calculated in a pair-interaction model including multiparticle Jahn-Teller contributions to the energy and dynamic matrix of the crystal. The model calculations performed using different values of the Jahn-Teller coupling constants show that the Jahn-Teller contribution to the energy of the crystal has a decisive influence on the formation of the structure and on the specific physical properties of KCuF3. © 1996 American Institute of Physics.