The symmetry of HK codes representing close-packed structures and the efficient generation of non-equivalent polytypes of a given length.
The HK representation of close-packed polytypes is studied as a binary code. It is shown that the HK code can be seen as operators forming a group. The neutrality condition is then translated to HK sequences that result in the identity operator. The symmetry of an HK word can be related to the space-group symmetry of the corresponding polytype. All HK code types corresponding to all possible close-packed space groups are reported. From a coding perspective, equivalent HK codes correspond to bracelet equivalent classes. An efficient algorithm with execution time constant per generated object is modified to generate all non-equivalent polytypes of a given length.
Estevez-Rams
Ernesto
E
Institute of Materials Research and Engineering, University of Havana, San Lazaro y L. CP 10400 C., Habana, Cuba. estevez@imre.oc.uh.cu
Martinez-Mojicar
Jennifer
J