Electronic properties of a zinc oxide nanotube under uniaxial tensile strain: a density functional theory study

In this article, density functional theory calculations were employed to investigate the electronic properties of (4,4) armchair zinc oxide single-walled nanotubes (ZNONTs) under uniaxial mechanical deformations. It was found that the highest-occupied molecular orbital and the lowest-unoccupied molecular orbital gap and the value of radial buckling will both decrease linearly with the increase of axial strain. The elongation of the ZNONT mainly originates from the decrease and increase of two characteristic bond angles rather than Zn-O ionic bond elongation. This mechanical behavior is very different from the uniaxial tensional processes of carbon nanotubes and silicon carbide nanotubes formed by covalent bonds. The partial densities of states of the Zn atom and O atom show that the unoccupied states are gradually left-shifted as ZNONT elongates from 0 to 15%. Neither Mulliken charge nor deformation density clearly changes with the different tension strains. Bond order analysis also indicates the bonding strength will decrease as the strain increases from 0 to 15%.