A comparison of PM3 semiempirical and B3LYP density functional methods for calculating carbon nanotube-hydrocarbon bond strengths

Carbon nanotube-hydrocarbon bond strengths are calculated using PM3 semiempirical and B3LYP density functional theories for various nanotube structures, link heteroatoms and hydrocarbon structures. Comparison of the results show that the same trends in bond strengths are obtained from the two theories. However, the magnitude of bond strengths, as well as the magnitude in the change in bond strengths when changing nanotube structures, link atom or hydrocarbon structures, does depend on the theory used in the calculation. Hence, calculations based on PM3 theory should focus solely on trends and not on quantitative results.