Method to Obtain the Character Tables of Nonsymmorphic Space Groups

A method is developed to obtain the character tables of nonsymmorphic space groups. The method is based on the possibility of obtaining all the irreducible representations of a group, if one knows all the irreducible representations of its invariant subgroup of index 2 or 3. It turns out that all the space groups have an invariant subgroup of index 2 or 3.