Abstract
Calculations of incoherent scattering factors for sodium, aluminium, argon and krypton have been carried out by direct integration over the impulse approximation Compton profiles (IACP). The authors compare their results with those obtained by the Waller-Hartree (WH) theory (1929). It is found that at low scattering angles, the IACP results differ significantly from the WH scattering factors.