The chirality of metal-encapsulated silicene-like nanotubes

The energy stability and electronic structures of (3,3) armchair metal-encapsulated SiNTs (M@SiNTs) are systematically studied by using DFT-GGA calculations. Results show that most the metal-encapsulated SiNTs with the same space group can be stabilized through doping by metal atoms with silicene-like structures. Compared with the different chirality, (4,0) zigzag M@SiNTs are more stable than (3,3) armchair M@SiNTs. The band gaps of (3,3) and (4,0) SiNTs are 1.06 eV and 0.06 eV, they are both semiconductors. But most (3,3) armchair and (4,0) zigzag M@SiNTs are conductors, except (3,3) Sn@SiNT, (4,0) K@SiNT and (4,0) Ba@SiNT are semiconductors with small value of band gaps. The interaction between encapsulated metal and silicon atoms makes out orbital hybridizations, and decreases the gap between valence band and conduction band. Finally, electronic structural analysis shows that metal atoms gain electrons and Si atoms lose electrons as a whole, some electrons transfer from Si to metal atoms.