The non-degenerate core structure of a ½⟨111⟩ screw dislocation in bcc transition metals modelled using Finnis–Sinclair potentials: The necessary and sufficient conditions

Abstract

It is shown that semi-empirical potentials for bcc metals based on the non-directional second-moment Finnis–Sinclair approximation are able to predict, as a matter of routine, the non-degenerate core structure for the perfect ½⟨111⟩ dislocation if they correctly describe the inter-string pair potential of a rigid multi-string Frenkel–Kontorova model for the corresponding ideal bcc lattice. We prove this by inspecting the previously published empirical potentials, and also by performing an extensive search in functional parameter space for an optimal parameterisation of the magnetic potential formalism for bcc ferromagnetic Fe.

Keywords:

• defect structures
• dislocation structures
• Fe-based alloys
• first-principles calculations
• interatomic potential
• molecular dynamic simulations

Acknowledgements

SC, PMD and HSV acknowledge the Paul Scherrer Institut – Forschungskommission for partial financial support. This work was also partly funded by the UK Engineering and Physical Sciences Research Council (EPSRC) and by the European Communities under the contract of Association between EURATOM and UKAEA. The views and opinions expressed herein do not necessarily reflect those of the European Commission. This work was carried out within the framework of the European Fusion Development Agreement (EFDA) Fusion Materials Modelling Programme.