On the application of least-squares refinement to complex structures--resolving enantiomorphous phase ambiguity.

Abstract

A least-squares refinement procedure has been proposed for resolving enantiomorphous ambiguity of noncentrosymmetric structures containing heavy atoms in a centrosymmetric arrangement. During the least-squares refinement of a pseudo-centrosymmetric image containing both enantiomorphs, the temperature factors of atoms in one enantiomorph shift in the same direction, while those of the other shift in the opposite direction. Accordingly the true structure can be distinguished easily from its enantiomorph. Tests on four unknown structures have shown that the method is very powerful.