Structure and Electronic Properties of Single Walled Nanotubes from AlAs (111) Sheets: A DFT Study
Wei WANG,Kai TAN*()
Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian Province, P. R. China
A series of AlAs nanotubes (NTs) can be formed by rolling up two dimensional periodic (111) single layer sheets, namely (n, 0) and (n, m) nanotubes. Optimized parameters of the atomic arrangement, energy levels and electronic structure of corresponding nanotubes of different types were calculated and compared by the density functional theory (DFT) method. The calculated results showed that strain energies (Es) are negative over most of the diameter range for the (n, 0) and (n, m) series, indicating that these NTs are more stable than a planar AlAs (111) single layer. The strain energy gradually decreases with increasing diameter. The calculated electronic band structures and density of states profiles reveal that the indirect band gaps (Eg) of armchair AlAs nanotubes gradually decreases with increasing diameter, which is distinct behavior from the zigzag nanotubes. The zigzag AlAs nanotubes feature a direct Eg with a peak value (2.11 eV) for a tube of radius 1.87 nm. The origin of the differences in band gaps could be attributed to the p-p coupling interaction between Al 3p orbitals in the conduction band of the AlAs zigzag nanotube.
Received: 12 September 2016
Published: 08 December 2016