Electronic properties of carbon nanotubes

In this book, we present study of electronic properties and binding energy/atom of zig-zag, armchair and chiral carbon nanotubes (CNTs) with open ends using SIESTA code. Firstly five zig-zag nanotubes i.e. CNT30, CNT40, CNT50, CNT60 and CNT70 were studied. B.E./atom increases with the increase in length of CNT and also with the increase in the indices of each subsequent zig-zag CNT. For HOMO & LUMO, there is consistent increase and decrease respectively with the increase in the length of CNT which overall leads to decrease in HOMO-LUMO gap. Similarly five armchair nanotubes i.e. CNT33, CNT44, CNT55, CNT66 and CNT77 were studied. B.E./atom increases with each subsequent higher indices armchair CNT. Finally three different sets of chiral CNTs are studied. For first set in each subsequent step the 'm' and 'n' indices is increased by one whereas for second and third set, 'm', 'n' indices is increased by one respectively. The B.E./atom was increasing with each higher indices chiral CNT in their respective set, whereas HOMO, LUMO & HOMO-LUMO gap shows certain trend in the first set of chiral nanotube whereas in other two sets of chiral nanotubes no clear trend is observed.