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Abstract: The structural and electronic properties of hydrogenated armchair and zigzag SWCNTs with carbon ad-dimer (CD) defect were investigated by means of the B3LYP hybrid density functional method using 6-31G∗ basis set. It is found that the chemisorptions of two hydrogen atoms inside and outside the CD defective SWCNTs are exothermic processes. Exohedral nanotube adsorption is energetically more favorable than endohedral adsorption. These results are in agreement with hydrogen on pristine nanotubes. The positional preference for the chemisorption of two hydrogen atoms is the same for the CD defective armchair and zigzag nanotubes. However, the reaction energy of two hydrogen atoms on the exterior sidewalls of CD defective SWCNTs is almost independent of the tube diameter. This is different from the results reported on pristine nanotubes. The calculated energy gaps indicate that the hydrogen-chemisorbed CD defective armchair tubes are always wide energy gap structures, while the hydrogen-chemisorbed CD defective zigzag tubes have significantly lower gaps. The HOMO–LUMO gap and reaction energy for the chemisorption of more hydrogen atoms on the exterior sidewalls of CD defective armchair SWCNTs were also explored. [ABSTRACT FROM AUTHOR]

Abstract: Based on the recently isolated and characterized nanotube-like D 5 h C90 fullerene, the nonclassical hept-C100 fullerene created by inserting symmetrically five C2 around the circumference of D 5 h C90 and its derivatives C100 X 10 (X =H, F, Cl, and Br) have been reported here. The geometrical structures and electronic properties of them are studied using density functional theory (DFT) at the B3LYP/6-31G∗ level of theory. The reaction energies, HOMO–LUMO gaps, and aromaticities all show that the nonclassical fullerene derivatives C100H10, C100F10, C100Cl10, and C100Br10 are molecules with high stability; the stable behavior resembles the well-known C50 X 10 (X =H, F, Cl, and Br). It is quite possible that they can be synthesized experimentally. [Copyright &y& Elsevier]