ON SPACE-GROUP FREQUENCIES

In compiling the space-group-frequency table of observed structures, retention of all the 230 space groups is advocated. This is based on some of the fundamental aspects of chirality. For cases both with space-group chirality (case A, eg. P4(1), P4(3) etc.) and without (case B, eg. P2(1), P2(1)2(1)2(1)), possible asymmetric distribution of observed structures over mirror equivalents cannot be ruled out. The need to specify a possible physical attribute to characterize a given crystal and correlate this to the absolute structure in case B is pointed out.