Coupled quantum–continuum analysis of crack tip processes in aluminum

Abstract A concurrent multiscale method is presented that couples a quantum mechanically governed atomistic domain to a continuum domain. The approach is general in that it is applicable to a wide range of quantum and continuum material modeling methodologies. It also provides quantifiable and controllable coupling errors via a force-based-coupling strategy. The applications presented here utilize an atomistic region that is governed by Kohn–Sham density functional theory and a continuum region governed by linear elasticity with discrete dislocation capabilities. As a validation we compute the core structure of a screw dislocation in aluminum and compare to previously published results. Then we investigate two crack orientations in aluminum and predict the critical load at which crack propagation and crack tip dislocation nucleation occurs. We compute critical loads with both LDA and GGA exchange correlation functionals and compare our results to popular empirical potentials in the context of classical continuum models. Overall this work aims to lay a foundation for future quantum mechanics-based investigations of crack tip processes involving Al alloys and impurity elements.

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