[en] The authors use the continuous formulation for the matrix Hartree-Fock method, called the generator-coordinate-Hartree-Fock method, to rephrase a theorem of Nakatsuji et al. concerning the improvement of the Hellmann-Feynman forces calculated with nuclei-centered GTO basis functions. It is shown that one does not need to increase the size of the basis set in order to obtain reliable Hellmann-Feynman forces, but just use a self-consistent set so that, starting with some s-type GTOs, the p-type GTOs are a subset of the derivatives of those s-type GTOS, and so on. The authors illustrate this feature in calculations on small diatomic molecules