On new settings in some centrosymmetric space groups (vol 212, pg 347, 1997)

Certain mistakes in the author's previous publication [1] have since been d etected. It appears that some of the space groups listed therein cannot acc ommodate the alternative new settings of unit cell, because in these cases, when coordinates of equivalent points are obtained with reference to the n ew setting, they do not form an orbit of the particular space group. In oth er words, the two-fold rotation relating the old and the suggested new sett ings of the unit cell does not leave the configuration of the symmetry elem ents of such a space group undisturbed. A corrected list of centrosymmetric space groups which do allow new settings and in which, consequently, pairs of 'polar' descriptions of structures are possible, is presented below. Th is list replaces the one that appeared in [1].