Chapter 12.2 Locating heavy-atom sites

In order to obtain phase information from isomorphous replacement (or from anomalous dispersion), it is necessary to locate the atomic positions of the heavy-atom (or anomalous) scatterers. The topics covered in this chapter include: the origin of the phase problem; the Patterson function; difference Fourier maps; treatment of errors; automated search procedures; and special complications such as lack of isomorphism, space-group problems and high levels of substitution.

Keywords: Fourier maps; Patterson functions; difference Fourier maps; heavy-atom location; isomorphism; isomorphous replacement; lack of isomorphism; noncrystallographic symmetry; phase problem