[en] Starting from the total Hamiltonian of the crystal we show how to calculate the unshielded electric field gradient, especially the electronic contribution, and determine the form of the temperature dependence of the quadrupole coupling constant in pure non-transition metals. Influences of ionic displacement correlations and from the anharmonicity of the potential are taken into account. We obtain explicit expressions for the temperature dependence of the quadrupole coupling constant in the low and high temperature limit. Especially in the low temperature region the agreement with experimental data is improved. (orig.)