Abstract
Automated generation of reasonable atomic-level interface models, for example, at a grain boundary, is generally computationally intensive partly because of the three degrees of freedom in a rigid-body translation (RBT) of one side of the interface against the other. We propose an algorithm to obtain reasonable interface models using as few first-principles calculations as possible. The valence charge densities of two surface slabs constituting the interface are calculated using first-principles calculations. The surface charge densities are filtered with an exponential function using a parameter λ to obtain the reaction front. Models where the overlap of filtered charge densities between the two slabs takes a local maximum are adopted as initial models with desirable RBTs, which are then relaxed using first-principles calculations to obtain a reasonable interface model. The proposed algorithm successfully generated reasonable initial models for three out of three orientations in 75% of homointerfaces of body-centered cubic, face-centered cubic, and hexagonal close-packed non-magnetic elementary metals. For the Al {001} Σ5 twist grain boundary, the present algorithm also reproduced γ-surface features of RBTs showing correct displacement shift complete lattice periodicity. Further modifications and improvements to this method are expected to accelerate automated interface model generation from a previously unexplored approach.
Highlights
Understanding the atomic configuration at an interface in materials or devices is critical for investigating properties through computational methods to find avenues for further improvement
Models where the overlap of filtered charge densities between the two slabs takes a local maximum are adopted as initial models with desirable rigid-body translation (RBT), which are relaxed using first-principles calculations to obtain a reasonable interface model
The atom coordinates were fixed in valence charge density (ρ) calculations, and all atom coordinates were relaxed in relaxation calculations to obtain a relaxed interface from the initial model obtained in the proposed algorithm
Summary
Understanding the atomic configuration at an interface in materials or devices is critical for investigating properties through computational methods to find avenues for further improvement. Kiyohara et al developed a virtual screening method using support vector regression.9 They used a brute-force approach by conducting calculations on a 3D grid of ξ, η, and ζ to obtain the relation between the atomic configuration near the interface and the grain boundary energy for a number of Cu tilt CSL grain boundaries and applied the same predictor to predict, with very little computational effort, the reasonable atomic configurations of other Cu tilt CSL grain boundaries and their energies. Once the set of translations, ξ, η, and ζ, for an extremum of the alternative function is obtained, these values are used to obtain an initial interface structure with an optimal RBT between the two surfaces, and an explicit first-principles calculation is conducted to relax the atoms and obtain a reasonable interface. This study only investigated interfaces where relaxation of atoms is treated by a first-principles calculation starting from RBT of cleaved models, we are aware that pursuing more vigorous optimization of atomic configurations at the interface is an important topic
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