In GED the diffraction intensities at a particular diffraction angle θ θ is described via a scattering variable defined as | s | = 4 π π λ λ sin ⁡ ⁡ ( θ θ 2 ) . The total intensity is then given as a sum of partial contributions: I tot ( s ) = I a ( s ) + I m ( s ) + I t ( s ) + I b ( s ) , where I a ( s ) results from scattering by individual atoms, I m ( s ) by pairs of atoms and I t ( s ) by atom triplets. Intensity I b ( s ) corresponds to the background which, unlike the previous contributions, must be determined experimentally. The intensity of atomic scattering I a ( s ) is defined as I a ( s ) = K 2 R 2 I 0 ∑ ∑ i = 1 N | f i ( s ) | 2 , where K = ( 8 π π 2 m e 2 ) / h 2 , R is the distance between the scattering object detector, I 0 is the intensity of the primary electron beam and f i ( s ) is the scattering amplitude of the atom i of the molecular structure in the experiment. I a ( s ) is the main contribution and easily obtained for known gas composition. Note that the vector s used here is not the same as the excitation error used in other areas of diffraction, see earlier.