Space group software

ELVES has been developed as an expert system, by James Holton and Tom Alber, to go from data collection frames to structure without human intervention and will obviate the need for intermediate space-group determination described above. Very recently, 12 different European sites have been collaborating to develop a software package known as DNA (automateD collectioN of datA) for the automatic collection and indexing of macromolecular diffraction data. Further information is available at the web site www.dna.ac.uk. 

The above mentioned parameters and some other parameters of the VD polyhedra can be determined using the software package TOPOS [16]. As input data, this software employs space group, unit-cell dimensions and atomic coordinates. 

Various software exists that outputs information on space groups. It is best to use two or more of these programs in tandem to check for consistency of results (Table 17.14). 

Nearly all unit cell refinement programs assume that a list of peak positions will be provided in some form. A personal favorite for quick unit cell refinement is the graphical Celref for Windows software of Jean Laugier and Bernard Bochu. Celref also understands space groups and includes a facility to automatically match HKL positions to observed peaks. For use of internal standard, the XLAT software of Bernhard Rupp, despite its age, is very effective. However,... 

Table 17.14 Available space group information software and databases.

The process of structure solution of an unknown material from powder data can be divided into several steps. First one must record the highest-quality data possible on a (ideally) pure sample. One must then determine the unit cell parameters from observed peak positions (several software packages exist to tackle this nontrivial step). The space group symmetry must then be determined from systematic absences. At this stage, one of a number of different routes can be followed. One... 

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