Coarse-grained molecular dynamic model for metallic materials

It is not yet straightforward to expand the time scale of molecular dynamics simulations in spite of recent progress in high-performance computing since time series of atomic motion cannot be parallelized easily. In this study, a novel coarse-grained molecular dynamic model is employed to scale up the time range of atomistic simulations for metallic materials. Basic mechanical and thermal properties of nickel including elastic constants, bulk modulus, shear modulus, Young modulus and melting point are well reproduced with the definition of the coarse-grained model. Moreover, it was found that single crystal plasticity occurring in the coarse-grained model compares very well with all-atom molecular dynamics simulations. This can be explained by the equality of the ratio in the generalized stacking fault energy curve between coarse-grained and all-atom models. Furthermore, a large-scale coarse-grained molecular dynamics simulation of the crystal growth was performed on the supercomputer as a practical example of the acceleration of simulation, in which a submicron-order crystal appears from the seed crystal in the undercooled melt. It is expected that the coarse-grained molecular dynamics method has a variety of applications in the future since it can handle calculations on such a large scale with relative ease.