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 definitiions streamlined.
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.