Introduction

The dislocation_monopole calculation style calculation inserts a dislocation monopole into an atomic system using the anisotropic elasticity solution for a perfectly straight dislocation. The system is divided into two regions: a boundary region at the system’s edges perpendicular to the dislocation line, and an active region around the dislocation. After inserting the dislocation, the atoms within the active region of the system are relaxed while the positions of the atoms in the boundary region are held fixed at the elasticity solution. The relaxed dislocation system and corresponding dislocation-free base systems are retained in the calculation’s archived record. Various properties associated with the dislocation’s elasticity solution are recorded in the calculation’s results record.

Version notes

  • 2018-09-25: Notebook added

  • 2019-07-30: Method and Notebook updated for iprPy version 0.9.

  • 2020-09-22: Notebook updated to reflect that calculation method has changed to now use atomman.defect.Dislocation.

Additional dependencies

Disclaimers

  • NIST disclaimers

  • This calculation method holds the boundary atoms fixed during the relaxation process which results in a mismatch stress at the border between the active and fixed regions that interacts with the dislocation. Increasing the distance between the dislocation and the boundary region, i.e. increasing the system size, will reduce the influence of the mismatch stresses.

  • The boundary atoms are fixed at the elasticity solution, which assumes the dislocation to be compact (not spread out, dissociated into partials) and to remain at the center of the system. An alternate simulation design or boundary region method should be used if you want accurate simulations of dislocations with wide cores and/or in which the dislocation moves long distances.

  • The calculation allows for the system to be relaxed either using only static energy/force minimizations or with molecular dynamic steps followed by a minimization. Only performing a static relaxation is considerably faster than performing a dynamic relaxation, but the dynamic relaxation is more likely to result in a better final dislocation structure.