Abstract: The system trial and error method (STEM) for crystal structure determination is a systematical method. It is different from other current direct methods that derive reflection phases individually from several known reflections. According to size of the molecular, intensity and extensity of relations between reflections, STEM derides reflections into many small solvable systems, so that of each reflection satisfy the probability requirement for phase determination in each of these systems. And on basis of Sayre equation, set up system's over-determined equation. Then, by means of trial and error method, find out the optimization to satisfy the system equation, thus the system's reflection phases be solved all at the same time.
A routine for crystal structure....