Linear Scaling DFT for defects in metals

Ponga, Mauricio; Ariza, Manuel R. Gómez; Ortiz, Michael; Bhattacharya, Kaushik

doi:10.1007/978-3-319-48237-8_35

Cited by 2 publications

(3 citation statements)

References 12 publications

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“…Find the corrector fields φ c p , ρ c p using (14) for each p ∈ P f , Find {λ q k } and {w q k } using Lanczos algorithm for each q ∈ P c , Find N e , ρ q for each p ∈ P f using ( 11), (12), until convergence of the electronic fields, Compute the forces on the RepAtoms P a , Update the position of the RepAtoms P a , until convergence of the atomic positions.…”

Section: Algorithm 1 Macrodft Algorithmmentioning

confidence: 99%

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Large scale ab-initio simulations of dislocations

Ponga

Bhattacharya

Ortiz

2020

Journal of Computational Physics

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We present a novel methodology to compute relaxed dislocations core configurations, and their energies in crystalline metallic materials using large-scale ab-intio simulations. The approach is based on MacroDFT, a coarse-grained density functional theory method that accurately computes the electronic structure but with sub-linear scaling resulting in a tremendous reduction in cost. Due to its implementation in real-space, MacroDFT has the ability to harness petascale resources to study materials and alloys through accurate ab-initio calculations. Thus, the proposed methodology can be used to investigate dislocation cores and other defects where long range elastic defects play an important role, such as in dislocation cores, grain boundaries and near precipitates in crystalline materials. We demonstrate the method by computing the relaxed dislocation cores in prismatic dislocation loops and dislocation segments in magnesium (Mg). We also study the interaction energy with a line of Aluminum (Al) solutes. Our simulations elucidate the essential coupling between the quantum mechanical aspects of the dislocation core and the long range elastic fields that they generate. In particular, our quantum mechanical simulations are able to describe the logarithmic divergence of the energy in the far field as is known from classical elastic theory. In order to reach such scaling, the number of atoms in the simulation cell has to be exceedingly large, and cannot be achieved with the state-of-the-art density functional theory implementations.

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Section: Algorithm 1 Macrodft Algorithmmentioning

confidence: 99%

“…al. [14,15] and has it roots in the linear scaling method of Suryanarayana et al [16]. The latter reformulates the original Kohn-Sham equations [17,18] into density matrix form, and then approximates the density matrix using spectral Gauss quadrature rules.…”

Section: Introductionmentioning

confidence: 99%

Large scale ab-initio simulations of dislocations

Ponga

Bhattacharya

Ortiz

2020

Journal of Computational Physics

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“…al. 48 , which calculates the electronic charge density and the total energy directly by performing Gauss quadratures over the spectrum of the Hamiltonian and in this way is capable to reach a linear complexity, also works for metallic systems 49 .…”

Section: Introductionmentioning

confidence: 99%

Linear scaling DFT calculations for large tungsten systems using an optimized local basis

Mohr

Eixarch

Amsler

et al. 2018

Nuclear Materials and Energy

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Density Functional Theory (DFT) has become the quasi-standard for ab-initio simulations for a wide range of applications. While the intrinsic cubic scaling of DFT was for a long time limiting the accessible system size to some hundred atoms, the recent progress with respect to linear scaling DFT methods has allowed to tackle problems that are larger by many orders of magnitudes. However, as these linear scaling methods were developed for insulators, they cannot, in general, be straightforwardly applied to metals, as a finite temperature is needed to ensure locality of the density matrix. In this paper we show that, once finite electronic temperature is employed, the linear scaling version of the BigDFT code is able to exploit this locality to provide a computational treatment that scales linearly with respect to the number of atoms of a metallic system. We provide prototype examples based on bulk Tungsten, which plays a key role in finding safe and long-lasting materials for Fusion Reactors. We believe that such an approach might help in opening the path towards novel approaches for investigating the electronic structure of such materials, in particular when large supercells are required.

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Linear Scaling DFT for defects in metals

Cited by 2 publications

References 12 publications

Large scale ab-initio simulations of dislocations

Large scale ab-initio simulations of dislocations

Linear scaling DFT calculations for large tungsten systems using an optimized local basis

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