Minimization of cross entropy: a tool for solving crystal structures

Abstract

A new algorithm for the solution of crystal structures via the principle of minimum cross entropy is described. This method is an extension of direct methods. Conventional direct methods are used to find an initial set of phases which are extended and refined by a search for the minimum-cross-entropy solution. This search is done directly in terms of the phases rather than the Lagrange multipliers used in most other approaches. It was tested by solving two structures, a small molecule and a macromolecule of 610 atoms in the asymmetric unit.