Study On The Structural And Electronic Properties Of Mercury Chalcogenide Clusters

II-VI semiconductor quantum dots have attracted much attention due to their unique physical properties and potential applications. The properties of mercury chalcogenides HgX (X=S, Se, Te) clusters are very similar to II-VI semiconductor quantum dots,and because mercury chalcogenide bulk material is a semimetal with the band gap equal to zero or near to,and semimetal to semiconductor transition can thus be produced by size quantization, the semimetal material can be made to active quantum dots light emitting devices and including the window frequency of broad band telecommunication., they play more important roles in application. Clusters look as bare quantum dots, it is the base of research quantum dots, and meanwhile, physical scientists also make attention on them. At present, ab initio studies on the mercury chalcogenide clusters are limited by capability of computer. Therefore, it is significant to further study on the properties of chalcogenide clusters.In this paper, using the principles method which based on density function theory (DFT),we calculated the ground states and properties ,as binding energy and energy gap, of (HgTe)n(1≤n≤8),(HgS)n(1≤n≤13)and (HgSe)n (1≤n≤8) clusters with the generalized gradient approximation (GGA).By calculation and analysis, we come to the following conclusions:(1) Calculating and analyzing (HgTe)n(1≤n≤8)clusters by DMOL3, compared to the results of CASTEP, they inosculate very well, so it is sure that we can research mercury chalcogenide clusters by DMOL3.(2) The geometrical structures of the ground state for (HgTe)n,(HgS)n and (HgSe)n(1≤n≤6)clusters exhibit similarity. However, there are small discrepancies in the length of bonds and bond angles between them. Structures of clusters are complex and the symmetry of them can hardly be observed. The initial structures of (HgS)n clusters (9≤n≤13) are given basing on structures of 1≤n≤8.(3)The binding energy of mercury chalcogenide clusters change with increasing of the size, it is fast when clusters is small (1≤n≤3).With increasing of the size, the binding energy increase instable and appear max and min value. There are some discrepancy changes between binding energy and energy gap of (HgTe)n,(HgS)n and (HgSe)n clusters with the size changes, with respective characteristic.(4)The complexity increase in the binding energy, energy gap of (HgTe)n, (HgS)n and (HgSe)n clusters ,with the increase of size, the correlation is weak.In this paper, the results of the geometrical structures and electronic properties should be verified developed, though we believe that they are helpful on understanding mercury chalcogenide clusters.