Using the Zn atom as an example, beyond the scopes of the impulse approximation and the inco herent scattering function approximation, we study the absolute value and the shape of the double differen tial nonresonance Compton scattering cross section of an X ray photon by an atom with the core of the d symmetry. We take into account the effects of radial relaxation of shells in the field of core vacancies and of elastic (Thomson and Rayleigh) scattering. Calculation results have a predictive character and, for the inci dent photon energies of 14.93 and 22.10 keV and the scattering angles of 141° and 133°, agree well with exper imentally determined values of the differential Compton scattering cross section.