Theoretical studies on the electronic structures and spectra of single silicon-doped SWCNTs

• Published in: Central European journal of chemistry Vol. 8; no. 3; pp. 587 - 593
• Main Authors: Gao, Peng, Yu, Yingying, Ni, Zhangqin, Teng, Qiwen
• Format: Journal Article
• Language: English
• Published: Heidelberg SP Versita 01.06.2010; Versita; De Gruyter
• Subjects: Aromaticity; Biochemistry; Biological and Medical Physics; Biophysics; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; DFT; Geochemistry; NMR spectra; Research Article; Si-doped SWCNTs; Stability; Si-doped SWCNTs; Stability; DFT; NMR spectra; Aromaticity
• ISSN: 1895-1066; 2391-5420; 1644-3624; 2391-5420
• DOI: 10.2478/s11532-010-0018-y

The equilibrium geometries and electronic structures of a series of SWCNTs doped with a silicon atom were studied by using density function theory (DFT). The most stable doping site of silicon predicted at B3LYP/6-31G(d,p) level was located near the boundary of the SWCNTs. The energy gaps of (3,3) C 48 , (3,3) C 60 and (3,3) C 72 were respectively decreased by 0.43, 0.25 and 0.14 eV after doping. Based on the B3LYP/6-31G(d) optimized geometries, the electronic spectra of the doped SWCNTs were computed using the INDO/CIS method. The first UV absorption at 973.9 nm of (5,5)-Si(L) (C 59 Si) compared with that at 937.5 nm of (5,5) (C 60 ) was red-shifted. The 13 C NMR spectra and nuclear independent chemical shifts (NICS) of the doped SWCNTs were investigated at B3LYP/6-31G(d) level. The chemical shift at 119.4 of the carbon atom bonded with the silicon atom in (3,3)-Si(L) (C 59 Si) in comparison with that at 144.1 of the same carbon atom in (3,3) (C 60 ) moved upfield. The tendency of the aromaticity (NICS = −0.1) for (3,3)-Si(H) (C 47 Si) with respect to that of the anti-aromaticity (NICS = 6.0) for (3,3) (C 48 ) was predicted.