The Role of Uniaxial Stress in the Formation of Benzene Nanothreads
River Leversee, University of Colorado Boulder
At extreme pressures, benzene and other cyclic hydrocarbons can form long polymeric structures known as carbon nanothreads through a topochemical reaction. Nanothreads are exceptionally strong, can be functionalized, and are promising materials for applications in energy storage. Uniaxial stress is understood to be an important factor in nanothread formation, but the exact influence of uniaxial stress on nanothread formation has proven difficult to explore experimentally and has not been investigated using ab initio methods. In this work, we have performed zero-temperature density functional theory optimizations of the structure of benzene under both uniaxial and hydrostatic conditions. The optimized structures provide insight into the effect of uniaxial stress on the carbon-carbon spacings between neighboring benzene molecules along the molecular stacking axes of the crystal. These carbon-carbon spacings can be used to predict the onset of reactive events in the crystal, which occur once C-C distances are reduced to a value of about 2.5 Angstroms. The optimized structures also provide initial geometries for ab initio molecular dynamics simulations, which allow for investigation of the influence of uniaxial stress on the intermediate structures, reaction pathways, and onset pressures of nanothread formation. This work outlines a new approach to investigating the influence of uniaxial stress on nanothread formation applicable to other cyclic hydrocarbons such as furan.
Abstract Author(s): River Leversee, J. Mathias Webber