Space Group of Tellurium and Selenium

Abstract
A group theoretical analysis is given for the symmetry of the crystal structure and Brillouin zone of tellurium and selenium. This is of particular interest because of the presence in the crystal of a threefold screw axis. Character tables for the group of the wave vector are given for various points of the Brillouin zone. Both the single group and the spin double group are treated. Compatibility relations are given.