Multiscale simulations in simple metals: A density-functional-based methodology

Choly, Nicholas; Lü, Gang; Weinan, E; Kaxiras, Efthimios

doi:10.1103/physrevb.71.094101

Cited by 109 publications

(85 citation statements)

References 31 publications

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“…Different combinations of quantum-mechanical and classical atomistic methods other than DFT/EAM may also be implemented. 9 The great advantage of the present implementation is its simplicity. It demands nothing beyond what is required for a DFT calculation and an EAM QC calculation.…”

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confidence: 99%

“…The total system can be relaxed by using the conjugate gradient approach on the DFT atoms alone, while fully relaxing the EAM atoms in region II and the displacement field in region III at each step. Similar to Choly et al, 9 an auxiliary energy function can be defined as…”

Section: ͕͑F͖͒ ͑1͒mentioning

confidence: 99%

“…The coupling between regions II and III is achieved seamlessly via the QC formulation, while the coupling between regions I and II is accomplished by a scheme recently proposed by Choly et al 9 Based on this coupling strategy, E͓I+II͔ can be written as…”

Section: ͕͑F͖͒ ͑1͒mentioning

confidence: 99%

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From electrons to finite elements: A concurrent multiscale approach for metals

2006

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We present a multiscale modeling approach that concurrently couples quantum-mechanical, classical atomistic, and continuum mechanical simulations in a unified fashion for metals. This approach is particularly useful for systems where chemical interactions in a small region can affect the macroscopic properties of a material. We discuss how the coupling across different scales can be accomplished efficiently, and we apply the method to multiscale simulations of an edge dislocation in aluminum in the absence and presence of H impurities. DOI: 10.1103/PhysRevB.73.024108 PACS number͑s͒: 71.15.Mb, 62.20.Mk, 71.15.Dx Some of the most fascinating problems in all fields of science involve multiple spatial and/or temporal scales: processes that occur at a certain scale govern the behavior of the system across several ͑usually larger͒ scales. In the context of materials science, the ultimate microscopic constituents of materials are ions and valence electrons; interactions among them at the atomic level determine the behavior of the material at the macroscopic scale, the latter being the scale of interest for technological applications. Conceptually, two categories of multiscale simulations can be envisioned, sequential, consisting of passing information across scales, and concurrent, consisting of seamless coupling of scales. 1 The majority of multiscale simulations that are currently in use are sequential ones, which are effective in systems where the different scales are weakly coupled. For systems whose behavior at each scale depends strongly on what happens at the other scales, concurrent approaches are usually required. In contrast to sequential approaches, concurrent simulations are still relatively new and only a few models have been developed to date. [1][2][3][4][5][6] A successful concurrent multiscale method is the quasicontinuum ͑QC͒ method originally proposed by Tadmor et al. 2 The idea underlying this method is that atomistic processes of interest often occur in very small spatial domains while the vast majority of atoms in the material behave according to well-established continuum theories. To exploit this fact, the QC method retains atomic resolution only where necessary and grades out to a continuum finite element description elsewhere. The original formulation of QC was limited to classical potentials for describing interactions between atoms. Since many materials properties depend explicitly on the behavior of electrons, such as bond breaking/ forming at crack tips or defect cores, chemical reactions with impurities, and surface reactions and reconstructions, it is desirable to incorporate appropriate quantum mechanical descriptions into the QC formalism. In this paper, we extend the original QC approach so that it can be directly coupled with quantum mechanical calculations based on density functional theory ͑DFT͒ for metallic systems. We refer to the new approach as QCDFT.The goal of the QC method is to model an atomistic system without explicitly treating every atom in the problem. 2,7 This is ...

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Section: ͕͑F͖͒ ͑1͒mentioning

confidence: 99%

Section: ͕͑F͖͒ ͑1͒mentioning

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From electrons to finite elements: A concurrent multiscale approach for metals

2006

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“…14,15 A number of practical applications of OFDFT to predict mesoscale materials properties have been reported in recent years. [14][15][16][17][18][19][20][21][22][23] OFDFT provides an efficient and robust approach to study large samples with many well. 52 The HC KEDF undoubtedly broadens OFDFT's range of applications.…”

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confidence: 99%

Density-decomposed orbital-free density functional theory for covalently bonded molecules and materials

Xia

Carter

2012

Phys. Rev. B

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We propose a density decomposition scheme using a Wang-Govind-Carter (WGC)-based kinetic energy density functional (KEDF) to accurately and efficiently simulate various covalently bonded molecules and materials within orbital free (OF) density functional theory (DFT). By using a local, density-dependent scale function, the total density is decomposed into a highly localized density within covalent bond regions and a flattened delocalized density, with the former described by semilocal KEDFs and the latter treated by the WGC KEDF. The new model predicts reasonable equilibrium volumes, bulk moduli, and phase ordering energies for various semiconductors compared to Kohn-Sham (KS) DFT benchmarks. The decomposition formalism greatly improves numerical stability and accuracy while retaining computational speed compared to simply applying the original WGC KEDF to covalent materials. The surface energy of Si (100) and various diatomic molecule properties can be stably calculated and also agree well with KSDFT benchmarks. This linear scaling, computationally efficient, density-partitioned/multi-KEDF scheme opens the door to large scale simulations of molecules, semiconductors, and insulators with OFDFT.2

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“…Recently, the embedding method has been implemented in the context of QM/MM simulations of metallic materials. 6,7 In the self-consistent embedding QM/MM theory, the Kohn-Sham ͑KS͒ density-functional theory ͑DFT͒ ͑KS-DFT͒ ͑Ref. 9͒ is employed to perform QM calculations.…”

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confidence: 99%