Methods of Obtaining Agreement between the Measured and Calculated Structure Amplitudes

Abstract

X-ray structure analysis does not determine directly the mean electron density of the crystal. Experiment gives only the moduli of the structure amplitudes. To construct an electron density series we need information about the phases (signs) of the amplitudes which is obtainable by the direct methods discussed in chapters III and IV, or by calculating structure amplitudes, if at least approximate atomic coordinates are known.