Quasistatic Stick-slip in Dislocation Core and Frenkel-Kontorova Chain

TL;DR

This paper uses atomistic simulations to reveal quasistatic stick-slip behavior in dislocation cores and models it with a one-dimensional Frenkel-Kontorova chain, highlighting a discontinuous order parameter jump.

Contribution

It demonstrates that dislocation core restructuring during shear can be modeled as a stick-slip transition using a simple 1D chain, linking atomistic and reduced models.

Findings

Dislocation cores exhibit intermittent quasistatic restructuring.

Stick-slip transition is reproduced in a 1D Frenkel-Kontorova chain.

Discontinuous jump in an order parameter signifies the transition.

Abstract

By means of atomistic simulations, we demonstrate that a dislocation core exhibits intermittent quasistatic restructuring during incremental shear within the same Peierls valley. This can be regarded as a stick-slip transition, which is also reproduced for a one-dimensional Frenkel-Kontorova chain under rigid boundary conditions. This occurs due to a discontinuous jump in an order parameter of the system, which signifies the extent of region forbidden for the presence of particles in the chain. The stick-slip phenomenon observed in the dislocation core is also shown to be reflected after dimensionality reduction of the multidimensional atomic coordinates, which provides a basis for comparison with the simple one-dimensional chain.