Locating heavy-atom sites

Abstract

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. This chapter is also available as HTML from the International Tables Online site hosted by the IUCr.