Hints for Space Group Searching

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It is almost never sensible to switch off the check-box labelled Include alternative settings of selected space group. In many space groups, it is possible to choose the unit cell axes or origin in more than one way (e.g. Pmm2, P2mm and Pm2m are different settings of the same space group) and the choice between them is essentially arbitrary (see Space Group).

•	Rhombohedral space groups can be expressed relative to hexagonal or rhombohedral axes. If rhombohedral axes have been used, the letter r is appended to the space group symbol, e.g. R3r.