Determining torsional and self-adhesion energy barriers. (a) Torsion: A simple five-atom carbyne system with an imposed curvature (κ = 0.016 to 0.395 Å-1, inset κ = 0.2 Å-1) is subject to incremental twist while tracking the potential energy. The cyclical energy change due to a 180° twist increases with initial curvature as shown, defining the energy barrier (indicated by arrows) to untwist a carbyne chain in the looped configuration. (b) Adhesion: Three short six-atom carbyne chains (to reflect a three-loop adhesion case) were brought into close proximity over time to determine the interchain adhesion energy barrier, defined as the depth of the potential energy well (indicated by arrows).
Cranford Nanoscale Research Letters 2013 8:490 doi:10.1186/1556-276X-8-490