dislocation_SDVPN calculation style

Lucas M. Hale, lucas.hale@nist.gov, Materials Science and Engineering Division, NIST.

Introduction

The dislocation_SDVPN calculation style predicts a dislocation’s planar spreading using the semidiscrete variational Peierls-Nabarro method. The solution finds the disregistry (difference in displacement above and below the slip plane) that minimizes the dislocation’s energy. The energy term consists of two primary components: an elastic component due to the dislocation interacting with itself, and a misfit component arising from the formation of a generalized stacking fault along the dislocation’s spreading.

Version notes

  • 2018-09-25: Notebook added

  • 2019-07-30: Notebook setup and parameters changed.

  • 2020-09-22: Notebook updated to reflect changes in the calculation method due to updates in atomman’s Volterra class solution generators. Setup and parameter definitions streamlined.

  • 2022-03-11: Notebook updated to reflect version 0.11.

Additional dependencies

Disclaimers

  • NIST disclaimers

  • The calculation method solves the problem using a 2D generalized stacking fault energy map. Better results may be possible by measuring a full 3D map, but that would require adding a new calculation for the 3D variation.

  • The implemented method is suited for dislocations with planar spreading. It is not suited for dislocations that spread on multiple atomic planes, like the a/2<111> bcc screw dislocation.

  • While the solution is taken at discrete points that (typically) correspond to atomic sites, the underlying method is still a continuum solution that does not fully account for the atomic nature of the dislocation.

Method and Theory

This calculation method is a wrapper around the atomman.defect.SDVPN class. More details on the method and theory can be found in the associated tutorial within the atomman documentation.