The probability distribution of X-ray intensities. III. Effects of symmetry elements on zones and rows

Abstract

A symmetry element that causes equivalent atoms to coincide in groups of n in a plane (or line) projection produces a zone (or row) of reflexions whose average intensity is n~, where ~ is the sum of the squares of the scattering factors of the atoms in the unit cell. The average for the general re- flexions is ~]; the difference between the zone (or row) average and the general average may be useful in the purely X-ray determination of space groups. The effects of simple symmetry elements on the probability distribution of the intensities are summarized in two tables.