Computational Study of Electric Dipole Moment and HOMO–LUMO Gap Energy of Some Isovalent functionalized (5, 0) Zigzag carbon nanotube

Functionalization is an important method to change electrical and thermodynamic properties of carbon nanotube. In this study, the effect of isovalent electron functionalization of a single-walled carbon nanotube (SWCNT) was studied with density functional theory. For this case, a (5, 0) zigzag SWCNT model containing 60 C atoms with 10 hydrogen atoms added to the dangling bonds of the perimeter carbons was used. To model functionalized CNT one terminal H atoms were replaced by –F, –OH, -Cl and -SH groups. All the functionalized CNTs have higher dipole moment with respect to the pristine CNT. The Gibbs free energy calculations demonstrate that except SH-CNT the other structures are more stable than pristine CNT. The optimized structure and molecular properties such as the HOMO-LUMO gaps, the dipole moments, and the density of state were calculated. Our results indicate that the HOMO–LUMO gap and electric dipole moment strongly respectively depends on the valence and electronegativity of the functional group on the nanotubes.