Structural transitions and electronic properties of the ultrathin SiC nanotubes under uniaxial compression

We report a structural transformation from zigzag to armchair in ultrathin SiC nanotubes under uniaxial compression. Our density functional theory calculations also reveal that an unusual type of fourfold-coordinated tubes corresponds to a distinct minimum on the transformation path and these tubes are all semiconducting with diameter-dependent indirect band gaps. Within the diameter range considered, the electronic properties of these three types of SiC nanotubes (zigzag, armchair, fourfold-coordinated) exhibit distinctly different behaviors.