The structural and electronic properties of HgmTen (mnot equaln=13, 16,\ud 19, and 28) clusters are calculated using density functional formalism\ud and the pseudopotential method within the generalized gradient\ud approximation. The initial structures of all the clusters are chosen to\ud be fragments of bulk phase HgTe with T-d symmetry. It is found that the\ud relaxed structures of Hg13Te16 and Hg16Te19 retain their initial\ud symmetry, whereas those of Hg16Te13, Hg19Te16,\ud Hg19Te28(=Hg16Te19+12Te), and Hg28Te19(=Hg16Te19+12Hg), due to the\ud Jahn-Teller distortions except for the last one, change to lower\ud symmetries. However, it is apparent that the 12 additional Te atoms in\ud the Hg19Te28 cluster act to stabilize the Hg19Te16 core, while the 12\ud additional Hg atoms in the Hg28Te19 cluster do not do so. It is also\ud found that all the clusters studied here are initially semimetals with\ud zero or very small highest occupied molecular orbital (HOMO) - lowest\ud unoccupied molecular orbital (LUMO) gaps. However, after structural\ud relaxation, Hg16Te13, Hg19Te16, Hg19Te28, and Hg28Te19 are\ud semiconductors, while the other two clusters with unchanged symmetry\ud are still semimetallic in nature. Therefore, as well as the size\ud quantization, the symmetry of a cluster would seem to be another\ud significant factor to determine its HOMO-LUMO gaps
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