Orbital-free density functional theory: Linear scaling methods for kinetic potentials, and applications to solid Al and Si

Chai, Jeng-Da; Lignères, Vincent L.; Ho, G. C.; Carter, Emily A.; Weeks, John D.

doi:10.1016/j.cplett.2009.03.064

Cited by 22 publications

(22 citation statements)

References 52 publications

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“…In terms of future development of the QM/MM method, we expect a continued improvement of the kinetic-energy functional 40,41 which is used in the interaction energy calculation. Such an improvement is crucial for the method to handle a broad class of materials.…”

Section: Discussionmentioning

confidence: 99%

Self-consistent embedding quantum mechanics/molecular mechanics method with applications to metals

2010

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We present a quantum mechanics ͑QM͒/molecular mechanics ͑MM͒ method for coupling Kohn-Sham density-functional theory with classical atomistic simulations based on a self-consistent embedding theory. The formalism and numerical implementation of the method are described. The QM/MM method is employed to study extended defects-a grain boundary and an edge dislocation in Al by focusing on hydrogen ͑H͒-defect interactions. We find that it is energetically more favorable for H impurities to segregate at the grain boundary and the dislocation core as opposed to the bulk. We provide direct first-principles evidence that both the grain boundary and the dislocation could serve as a "pipe" to accelerate H diffusion and shed light on the corresponding atomistic mechanisms. The results demonstrate that the QM/MM method is a powerful approach in dealing with extended defects in materials.

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Section: Discussionmentioning

confidence: 99%

Self-consistent embedding quantum mechanics/molecular mechanics method with applications to metals

2010

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“…The large computational requirements of QMD generally restrict its applications to relatively low temperatures. Through the use of gradient-corrected, non-local kinetic energy functionals, orbital-free density-functional calculations [12] have accurately simulated solids, like Al and Si, at room temperature. For this study, we restrict the OFMD to a semiclassical formulation at the Thomas-Fermi-Dirac level, which permits its extension to much higher temperatures and densities.…”

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confidence: 99%

Quantum molecular dynamics simulations of transport properties in liquid and dense-plasma plutonium

et al. 2011

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We have calculated the viscosity and self-diffusion coefficients of plutonium in the liquid phase using quantum molecular dynamics (QMD) and in the dense-plasma phase using orbital-free molecular dynamics (OFMD), as well as in the intermediate warm dense matter regime with both methods. Our liquid metal results for viscosity are about 40% lower than measured experimentally, whereas a previous calculation using an empirical interatomic potential (modified embedded atom [LANL publication number: LA-UR-10-07728]

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“…) Nevertheless, the last two decades have witnessed a flurry of interest in OFDFT; as computer power grows, larger and larger systems can be simulated by OFDFT thanks to its favorable linear scaling of computational time with respect to the size of the electronic system. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] In particular, OFDFT is indispensable for embedding approaches, where OFDFT is used to describe both the large surrounding environment as well as the interaction between the environment and a smaller active region. [18][19][20][21] Most of the research activity in orbital-free DFT has been devoted to static properties.…”

Section: Introductionmentioning

confidence: 99%

Dynamic kinetic energy potential for orbital-free density functional theory

Neuhauser

Pistinner

Coomar

et al. 2011

The Journal of Chemical Physics

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A dynamic kinetic energy potential (DKEP) is developed for time-dependent orbital-free (TDOF) density function theory applications. This potential is constructed to affect only the dynamical (ω ≠ 0) response of an orbital-free electronic system. It aims at making the orbital-free simulation respond in the same way as that of a noninteracting homogenous electron gas (HEG), as required by a correct kinetic energy, therefore enabling extension of the success of orbital-free density functional theory in the static case (e.g., for embedding and description of processes in bulk materials) to dynamic processes. The potential is constructed by expansions of terms, each of which necessitates only simple time evolution (concurrent with the TDOF evolution) and a spatial convolution at each time-step. With 14 such terms a good fit is obtained to the response of the HEG at a large range of frequencies, wavevectors, and densities. The method is demonstrated for simple jellium spheres, approximating Na(9)(+) and Na(65)(+) clusters. It is applicable both to small and large (even ultralarge) excitations and the results converge (i.e., do not blow up) as a function of time. An extension to iterative frequency-resolved extraction is briefly outlined, as well as possibly numerically simpler expansions. The approach could also be extended to fit, instead of the HEG susceptibility, either an experimental susceptibility or a theoretically derived one for a non-HEG system. The DKEP potential should be a powerful tool for embedding a dynamical system described by a more accurate method (such as time-dependent density functional theory, TDDFT) in a large background described by TDOF with a DKEP potential. The type of expansions used and envisioned should be useful for other approaches, such as memory functionals in TDDFT. Finally, an appendix details the formal connection between TDOF and TDDFT.

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Orbital-free density functional theory: Linear scaling methods for kinetic potentials, and applications to solid Al and Si

Cited by 22 publications

References 52 publications

Self-consistent embedding quantum mechanics/molecular mechanics method with applications to metals

Self-consistent embedding quantum mechanics/molecular mechanics method with applications to metals

Quantum molecular dynamics simulations of transport properties in liquid and dense-plasma plutonium

Dynamic kinetic energy potential for orbital-free density functional theory

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