Crystal structure determination

Abstract

Determination of crystal structures from diffraction requires first the solution of the crystallographic phase problem. Solving the phase problem is equivalent to the determination of atomic positions in the crystal structure and, as such, it is an essential part of the structure determination. Numerous methods have been developed for this purpose. They can be classified into several classes: ab initio methods include Patterson method, direct methods and dual space iterative algorithms. These methods do not require much more information than the diffraction data. Direct space methods like simulated annealing and genetic algorithms are used mostly for structure solution from powder diffraction data. They can handle lower data quality, but they require additional information, typically molecular connectivity.