  The ultrathin one-dimensional sp3 diamond nanothreads (NTHs), as successfully
synthesised recently, have greatly augmented the interests from the carbon
community. In principle, there can exist different stable NTH structures. In
this work, we studied the mechanical behaviours of three representative NTHs
using molecular dynamics simulations. It is found that the mechanical
properties of NTH can vary significantly due to morphology differences, which
are believed to originate from the different stress distributions determined by
its structure. Further studies have shown that the temperature has a
significant impact on the mechanical properties of the NTH. Specifically, the
failure strength/strain decreases with increasing temperature, and the
effective Young's modulus appears independent of temperature. The remarkable
reduction of the failure strength/strain is believed to be resulted from the
increased bond re-arrangement process and free lateral vibration at high
temperatures. In addition, the NTH is found to have a relatively high bending
rigidity, and behaves more like flexible elastic rod. This study highlights the
importance of structure-property relation and provides a fundamental
understanding of the tensile behaviours of different NTHs, which should shed
light on the design and also application of the NTH-based nanostructures as
strain sensors and mechanical connectors.
