Total energy calculations on zinc sulphide polytypes

The authors report the results of first-principles pseudopotential calculations of the total energies of the (1), ( infinity ), (2211), (2) and (3) polytypes of ZnS. These results are compared with previous work on SiC polytypes. The lowest energy ZnS polytype is calculated to be ( infinity ), in agreement with the experimental observation that ( infinity ) is the stable low temperature modification. They find that, in contrast to SiC, all ZnS polytypes are very close in energy. They discuss the implications of their results for theories of polytypism in ZnS.