The symmetry of HK codes representing close-packed structures and the efficient generation of non-equivalent polytypes of a given length

HK codes representing close-packed polytypes are studied as operators forming a group. The symmetry of the HK codes can be related to the space group of the corresponding polytype. Equivalent polytypes correspond to bracelet equivalent classes in the binary HK code. An algorithm for bracelet generation, with execution time constant per generated object, is modified to exhaustively generate all non-equivalent polytypes of a given length.