If these are compared to the coefficients in the electron density equation:

it is apparent that whereas the electron density function produces peaks at locations (x_i, y_i, z_i) that are proportional to f_i (the scattering power of atom i), the Patterson function produces peaks at locations (x_i-x_j, y_i- y_j, z_i-z_j) that are proportional to f_if_j:

Therefore, the Patterson function produces peaks at the end-points of atom-atom vectors. The height of each of these peaks is proportional to the product of the atomic numbers of the two atoms between which the vector is being constructed. Peaks due to vectors between two “heavy” atoms will “stand out” against all the other vector peaks and will be easy to identify.