Holosymmetric space group

The point group P C PBL and when P = PBL (which is so for a holosymmetric space group) the points and lines of symmetry mark out the basic domain il of the Brillouin zone. When... 

In Sect. 3.1.2 points and fines of symmetry in the Brillouin zone were defined for the case when F = F° (holosymmetric space groups, in particular 0 and D f. In the same manner the points and lines of symmetry may be defined for the point group F C F°. Then, instead of the basic domain of the BriUouin zone the representation domain is introduced. 

As will be illustrated in subsequent chapters, numerous variants of the apatite atomic arrangement exist. The variant structures, all sub-symmetries of the atomic arrangement of apatite sensu stricto, result principally from chemical substitutions (or, in the case of pure chlorapatite and pure hydroxylapatite, lack of chemical substitutions) on cation and/or anion sites. To provide a framework for discussion, we here describe the holosymmetric apatite structure, in space group PGs/m ( 176). 

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