Fluorinated single-wall carbon nanotubes

Fluorinated armchair (10,10) and zigzag (18,0) single-wall carbon nanotubes (F-SWNT) of ${\mathrm{C}}_2\mathrm{F}$ stoichiometry with five different fluorine atom decorations are studied using density-functional theory and periodic boundary conditions. The most stable armchair F-SWNT isomers $(1a$ and $5a)$ are metallic and have $\pi$ bond chains parallel to the tube axis. Isomer $5a$ carries every second fluorine atom inside the tube and is $5\hspace{0.5em}{\mathrm{kcal}\mathrm{}\mathrm{mol}}^{-1}$ more stable than $1a.$ Fluorinated zigzag tubes are not metallic. The isomer with helical zigzag conjugated $\pi$ bonds is the most stable zigzag F-SWNT, but is less stable than $1a.$ Depending on the fluorination pattern and the tube chirality, the band gaps of the F-SWNT’s vary from 2.7 to 0 eV.