The minimal nanowire: Mechanical properties of carbyne

Advances in molecular assembly are converging to an ultimate in atomistic precision -nanostructures built by single atoms. Recent experimental studies confirm that single chains of carbon atoms -carbyne- exist in stable polyyne structures and can be synthesized, representing the minimal possible nanowire. Here we report the mechanical properties of carbyne obtained by first-principles-based ReaxFF molecular simulation. A peak Young's modulus of 288GPa is found with linear stiffnesses ranging from 64.6-5 N/m for lengths of 5-64 angstrom. We identify a size-dependent strength that ranges from 11GPa (1.3 nN) for the shortest to a constant 8GPa (0.9 nN) for longer carbyne chains. We demonstrate that carbyne chains exhibit extremely high vibrational frequencies close to 6 THz for the shortest chains, which are found to be highly length-dependent. Copyright (C) EPLA, 2011