Method and system for analyzing diffraction data from crystalline systems

A method for exploiting space group symmetry in the indexing of powder diffraction data, by selecting a crystal system to search, then grouping possible indexing solutions compatible with this crystal system into powder extinction classes having the same pattern of systematic absences, and performing separate indexing solution searches within at least two of said powder extinction classes.

A system for indexing a set of powder diffraction data, comprising:

• a general purpose processor, wherein the processor is configured to divide the data into a plurality of powder extinction classes having the same pattern of systematic absences, and wherein the processor is further adapted to search each powder extinction class over a calculated peak number range.

A system for indexing a set of powder diffraction data, comprising:

• a memory storing diffraction data;
• and
• at least one processor configured to read data from and write data to the memory and further configured to analyze said data to produce indexing solutions starting at solutions with a small number of calculated peaks and progressing toward solutions with a larger number of calculated peaks.

A method of analyzing diffraction data comprising:

• generating a plurality of indexing solutions from said diffraction data;
• ranking said indexing solutions by calculating a figure of merit for at least some of said indexing solutions, wherein said figure of merit is constructed such that it tends to rank solutions with smaller numbers of calculated reflections higher.