Explanatory Notes for the Use of the Main Data-Table

Abstract

The structure types in the Main Data-Table are dassified according to:

• (1) Increasing space group number. The space group number is included in the page number, and is indicated within parentheses before the Hermann-Mauguin symbol on the first line of each data set (type classification line).

• (2) Increasing sum of multiplicities of all, fully or partly occupied atom sites in the structure (number of atoms in the unit cell for structures with only fully occupied sites). This number is included in the Pearson code (see Chapter 1.1.), which is indicated at the end of each type classification line. Note that for trigonal structures based on an R Bravais lattice the sum of multiplicities refers to the triple hexagonal cell and that hydrogen atoms in H₂O or NH₃ molecules, OH- or NH₄+ groups, are not considered here.

• (3) Increasing number of different letters in the Wyckoff sequence. The complete Wyckoff sequence, i.e. the sequence of letters of all, fully or partly occupied atom sites in the standardized structure description, is to be found at the centre of the type classification line.

• (4) Increasing value of the CG parameter.