First Principles Study Of Nano-materials

Based on the density functional theory(DFT),we studied carbon nanotubes doped with K, III-V phosphide nanotubes (BP, AlP, and GaP), as well as ZnO nanowires adsorbed with CO by using first principle method. After doped with K, small deformation of nanotubes due to intercalation and charge transferred between K and C. The Femi level increased with doping position and doping density while the band gap decreased. The study showed zigzag nanotubes of AlP and GaP mostly had direct band gap,armchair nanotubes had indirect band gap,while BP nanotubes mostly had direct band gap.The band gap of three kinds of nanotubes all increased with the diameter. Through the exponential function fitting,we can see the band gap of AlP (n n) nanotubes tended to 2.195ev. When ZnO nanowires were in the adsorption of CO gas, chemisorption and physisorpton existed. When the C atoms were close to the nanowires, it was chemisorption. It was found that the chemisorption enhanced the Fermi level and increased the band gap of ZnO nanowires.