The fundamental requirement introduced by eq. 3 is that the density gradient vector and electric field vector are parallel in every point in space. This condition is obviously fulfilled for free atoms and their ions. According to our preliminary computations, this condition is also met for the valence region of a molecule. On the other hand, the gradient theorem (eq. 1) holds only for the density resulting from computational methods that comply to both Hellmann-Feynman theorem and Feynman electrostatic expression for atomic force . The vital role of this condition for the accuracy of the quantum chemical computations has been discussed in other works from this laboratory.