Atomistic simulations of energies for arbitrary grain boundaries. Part I: Model and validation

SY Li and L Yang and CM Lai, COMPUTATIONAL MATERIALS SCIENCE, 161, 330-338 (2019).

DOI: 10.1016/j.commatsci.2019.02.003

Grain boundary (GB) energies are important data for understanding and predictive modeling of thermal and mechanical behaviors in polycrystalline materials. In this study, a cutoff sphere molecular dynamics model is proposed to calculate the energies of arbitrary GBs. This model eliminates the effect of interaction between free surface and GB in a bicrystal cell by excluding the surface region in the energy computation. The model is tested for four groups of coincident site lattice (CSL) GBs with low-to-medium coincidence index and non-CSL GBs in aluminum. The results show that, at a fraction of computation time as of the original sphere model, the cutoff sphere model without rigid body translation (RBT) provides approximate energy predictions that agree with experimental results and those of the classical block model adopting periodic boundary conditions. The good performance of the cutoff sphere model for non-CSL GBs lies in its faithful reproduction of characteristic structure units and resulting quasi-periodicity in the GB structures. The applicability to arbitrary GBs renders the model an attractive tool to construct energy datasets useful for material behavior simulations. Further improvement in the accuracy of energy predictions is shown to be possible by incorporating RBT at the expense of significantly-increased computational cost.

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