Atomistic-continuum Method Research Articles

Composite Grid Atomistic Continuum Method: An Adaptive Approach to Bridge Continuum with Atomistic Analysis

Composite Grid Atomistic Continuum Method: An Adaptive Approach to Bridge Continuum with Atomistic Analysis

A Dynamic Atomistic–Continuum Method for the Simulation of Crystalline Materials

We present a coupled atomistic–continuum method for the modeling of defects and interface dynamics in crystalline materials. The method uses atomistic models such as molecular dynamics near defects and interfaces, and continuum models away from defects and interfaces. We propose a new class of matching conditions between the atomistic and the continuum regions. These conditions ensure the accurate passage of large-scale information between the atomistic and the continuum regions and at the same time minimize the reflection of phonons at the atomistic–continuum interface. They can be made adaptive by choosing appropriate weight functions. We present applications to dislocation dynamics, friction between two-dimensional crystal surfaces, and fracture dynamics. We compare results of the coupled method and of the detailed atomistic model.

Atomistic-continuum simulation of nano-indentation in molybdenum

Simulations of nano-indentation in bcc molybdenum are performed using a coupled atomistic-continuum method and a multi-body interatomic potential which includes angular forces. The indenter is flat and rigid while the indented material is a single crystal having its ⦑100⦒ and ⦑111⦒ directions respectively parallel to the indentation direction, in separate simulations. Indentation is accommodated by elastic deformation of the surface, up to an indenter displacement of about 6 A, and by nucleation of crystalline defects for deeper indents. When indented in the ⦑100⦒ direction, the crystal twins under the indenter, while indentation in the ⦑111⦒ direction produces dislocation nucleation from the stress concentration sites at the indenter edge. The critical loads for these events are computed and the nucleation mechanism is observed. The results are compared with available experimental data.