Is the molecular statics method suitable for the study of nanomaterials? A study case ofnanowires

Abstract

Both molecular statics and molecular dynamics methods were employed to study themechanical properties of copper nanowires. The size effect on both elastic and plasticproperties of square cross-sectional nanowire was examined and compared systematicallyusing two molecular approaches. It was found consistently from both molecular methodsthat the elastic and plastic properties of nanowires depend on the lateral size ofnanowires. As the lateral size of nanowires decreases, the values of Young’s modulusdecrease and dislocation nucleation stresses increase. However, it was shown thatthe dislocation nucleation stress would be significantly influenced by the axialperiodic length of the nanowire model using the molecular statics method whilemolecular dynamics simulations at two distinct temperatures (0.01 and 300 K)did not show the same dependence. It was concluded that molecular statics asan energy minimization numerical scheme is quite insensitive to the instabilityof atomic structure especially without thermal fluctuation and might not be asuitable tool for studying the behaviour of nanomaterials beyond the elastic limit.