The model based on the assumption of the existence of an interatomic distance-dependent, Ž local, effective crystal field applied to the alkaline metals Int. J. Quantum Chem. 52, Ž .. Ž 321᎐328 1994 is modified and applied to the diamondlike structure crystals C, Si, Ge, . Sn . In the referred to model, a part of the electron density was missedᎏnot included in Ž . the calculation the density in the spaces between the shells . Such an approach could be used for the alkaline metals, but for the covalent crystals, this is a bad approximation. To avoid that problem, we assumed that the atom shells can overlap in such a way that the entire electron density is taken into the calculation. In this case, the electron density is ''moved'' from the outside of the shells mostly into the interatomic bond region. We applied the modified model to the calculation of the binding energy and the bulk modulus for the diamondlike crystals. The results show that well-chosen parameters allows one to reproduce the proper values of the binding energy at the equilibrium position. The bulk moduli calculated for these crystals are in quite good agreement with Ž . Ž . ones calculated as regular crystal structure B s 1r3 C q 2 C , where C and C 11 12 11 12 are elastic constants.