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A Semiempirical Study of Carbon Nanotubes with Finite Tubular Length and Various Tubular Diameters
Author(s) -
Wang BoCheng,
Wang HoungWei,
Lin IChun,
Lin YunShan,
Chou YuMa,
Chiu HounLin
Publication year - 2003
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.200300132
Subject(s) - zigzag , carbon nanotube , homo/lumo , band gap , chemistry , molecular physics , nanotechnology , electronic band structure , condensed matter physics , materials science , crystallography , geometry , optoelectronics , physics , mathematics , organic chemistry , molecule
A semiempirical PM3 quantum computational method has been used to generate the electronic and optimized geometrical structure of SWNT of zigzag and armchair types. We shed light on the electronic structures of SWNT with various diameters and lengths of the tube. Particularly, the calculated HOMO, LUMO and band‐gap of SWNT are not monotonic but exhibit a well‐defined oscillation, which depends on the tubular diameter and the tubular length. Calculated HOMO, LUMO and band‐gap of the zigzag SWNTs have oscillated with tubular diameter as they contain an odd or even number of benzenoids in the circular plane of the carbon nanotube. The zigzag SWNTs with an odd number of benzenoids have a higher band‐gap than those of SWNTs with an even number of benzenoids in the circular plane of the carbon nanotube. Calculated results also reveal that the tubular length in the zigzag SWNTs influences the band‐gaps very little. For the armchair SWNT, calculated HOMO, LUMO and band‐gap contained the oscillate depending on the number of carbon sections in the tubular length axis. Their repeat sections are 3 n ‐1, 3 n and 3 n +1. The armchair SWNT with 3 n +1 sections has a high band‐gap while the SWNTs with 3 n ‐1 sections have a low band‐gap. The tubular diameters of armchair SWNT influence the HOMO, LUMO and band gap very little.