Generalized stacking fault energy surfaces and dislocation properties of aluminum

TL;DR

This study combines first-principles DFT and EAM calculations within a generalized Peierls-Nabarro model to analyze dislocation core properties in aluminum, revealing relationships between core structure and Peierls stress.

Contribution

It introduces a comprehensive approach using DFT and EAM to study dislocation cores in aluminum, highlighting the limitations of EAM in predicting fine core structures.

Findings

EAM captures gross trends but not detailed core structures.

Peierls stress correlates with the ratio of core width to atomic spacing.

Core properties depend on the energy calculation method used.

Abstract

We have employed the semidiscrete variational generalized Peierls-Nabarro model to study the dislocation core properties of aluminum. The generalized stacking fault energy surfaces entering the model are calculated by using first-principles Density Functional Theory (DFT) with pseudopotentials and the embedded atom method (EAM). Various core properties, including the core width, splitting behavior, energetics and Peierls stress for different dislocations have been investigated. The correlation between the core energetics and dislocation character has been explored. Our results reveal a simple relationship between the Peierls stress and the ratio between the core width and atomic spacing. The dependence of the core properties on the two methods for calculating the total energy (DFT vs. EAM) has been examined. The EAM can give gross trends for various dislocation properties but fails to predict the finer core structures, which in turn can affect the Peierls stress significantly (about one order of magnitude).