Theoretical study of position-dependent defect formation in a single-walled carbon nanotube: Stability towards an open end

TL;DR

This study investigates how point defects in single-walled carbon nanotubes vary in stability near open ends, using computational methods to assess defect formation and propose a defect-fixing model.

Contribution

It introduces a model for defect fixation at nanotube open ends based on position-dependent defect stability, validated by multiple computational approaches.

Findings

Defects are more stable closer to the SWNT opening end.

Semi-empirical PM3 method is sufficiently accurate for defect studies.

Empirical Brenner potential shows significant errors in defect formation predictions.

Abstract

Point defects, including atom vacancy, add atom and Stone-Wale defect, close to a (5, 5) single-walled carbon nanotube (SWNT) end were studied by DFT, semi-empirical PM3 method and empirical Brenner Potential. It is found that closer to the SWNT opening end more stable these defects are. Based on these calculations, a model about fixing defects on a growing SWNT by defects diffusing to the SWNT opening end was proposed. Furthermore, calculations also show that, similar to the DFT calculation, semi-empirical PM3 method is accurate enough for studying defect formation in SWNT. In contrast, the results based on the empirical Brenner potential show large errors and sometimes even not correct in quality.