Multiscale modeling of fracture: Buckingham catastrophe and remedy

Modified interatomic potential, namely Coulomb-Buckingham potential with remedy term, is used in the multiscale modeling and simulation of a centercracked specimen made of barium titanate (BaTiO3) and magnesia (MgO) under monotonically increasing loading. The specimen is decomposed into a far field, a near field and a crack-tip region. The analytical solution in the far field from linear elastic fracture mechanics (LEFM) is utilized to specify the boundary conditions at the interface between the near field and the far field. The solution of the near field is based on Atomistic Field Theory (AFT) and Generalized Atomistic Finite Element Method (GAFEM). In the crack-tip region, molecular dynamics (MD) simulation is employed. These methodologies are integrated to simulate a mixed mode fracture of barium titanate and magnesia. An extra r^-12 term is added to the original Coulomb-Buckingham potential models as a remedy for Buckingham Catastrophe. The remedy term eliminates the unphysical illusion: collision between two oxygen atoms when their distance becomes smaller than a critical value, Buckinghan threshold. The work shows the comparison of simulation results from two different potentials.