“…A simpler way of incorporating screening, the second term in equation (3,11 ), is to assume a charge density for the target ( atom in general or unit cell for solids) in which the reduced potential will take the form of a Yukawa expression in which the nuclear potential is attenuated exponentially as a function of distance r from the nucleus: (3,13) where r 0 is the screening radius. The angular distribution of the elastic scattering is:…”