Computer simulation of conductive linear sulfur chains confined in carbon nanotubes

Abstract

Recent experimental studies have shown that when sulfur is confined within a carbon nanotube (CNT) of appropriate diameter it forms a covalently bonded linear chain, and this confined one-dimensional sulfur phase is metallic. Such one-dimensional phases of sulfur are not observed in the bulk material, but at pressures in excess of 83 GPa bulk sulfur does form a metallic monoclinic phase. This suggests that the 1-D conducting phase formed in confinement may arise from high pressures arising due to the strong confinement. Here we report atomistic molecular dynamics of sulfur within (8,0) CNTs, using a recently derived statistical method for calculations of the pressure tensor, we find axial pressure component values as high as bar (800 GPa) for the SWLJ case. We decompose the pressure into contributions from sulfur–sulfur (S–S) and sulfur–carbon (S–C) interactions, and find that S–S interactions are strongly attractive, while S–C interactions are strongly repulsive.

Keywords:

• Sulfur
• high-pressure
• confinement

Acknowledgements

We thank Professor Katsumi Kaneko for permission to reproduce Figure 1. We thank Professor Adri van Duin for his help with the ReaxFF potential.

Notes

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the U.S. National Science Foundation [grant number CHE-1012780].