Local dynamics of the lattice is taken into consideration to modify the original Einstein model of lattice dynamics, and the modified Einstein model is tested by evaluating the thermodynamic properties of crystalline KBr. Specifically, the thermal expansion, thermal expansion coefficient and specific heat at constant volume have been evaluated as functions of temperature at atmospheric pressure for crystalline KBr using a realistic potential of the formA1R−9+A2R−6±A3R−1, and normal-mode frequencies obtained from local dynamics of two particles allowed to oscillate in a static potential field due to all the rest of particles, assumed at rest in their mean positions. The temperature dependence of these thermodynamic functions is examined in comparison with the available experimental data, and reasonable agreement is observed.