New hexagonal structure for silicon atoms
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- Naji, S., Belhaj, A., Labrim, H. et al. Eur. Phys. J. B (2012) 85: 373. doi:10.1140/epjb/e2012-30520-5
Motivated by recent experimental and theoretical works on silicene and its derived materials and based on the exceptional Lie algebra G2 we propose a new hexagonal symmetry producing the (√3 × √3)R30° superstructure for silicon atoms. The principal hexagonal unit cell contains twelve atoms instead of the usual structure involving only six ones and it is associated with the G2 root system. In this silicon atom configuration appears two hexagons of unequal side length at angle 30°. This atomic structure can be tessellated to exhibit two superstructures (1 × 1) and (√3 × √3)R30° on the same atomic sheet. To test this double hexagonal structure, we perform a numerical study using Ab-initio calculations based on FPLO9.00-34 code. We observe that the usual silicon electronic properties and the lattice parameters of planar geometry are modified. In particular, the corresponding material becomes a conductor rather than zero gaped semi-conductor arising in single hexagonal structure. Although the calculation is done for silicon atoms, we expect that this structure could be adapted to all two dimensional materials having a single hexagonal flat geometry.