Ab initio investigation of the Peierls potential of screw dislocations in bcc Fe and W

Ventelon, Lisa; Willaime, F.; Clouet, Emmanuel; Rodney, David

doi:10.1016/j.actamat.2013.03.012

Cited by 123 publications

(124 citation statements)

References 66 publications

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“…The Peierls plot for the GAP potential shows a single saddle point in qualitative accordance with earlier DFT findings 20 , whereas the Mendelev pathway has a double hump due to an incorrectly stabilised splitcore structure 97 . The asymmetry in the barrier plot of -TABLE IV.…”

Section: G Gamma Surfaces and Dislocationssupporting

confidence: 72%

Achieving DFT accuracy with a machine-learning interatomic potential: Thermomechanics and defects in bcc ferromagnetic iron

Dragoni

Daff

Csänyi

et al. 2018

Phys. Rev. Materials

246

224

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We show that the Gaussian Approximation Potential machine learning framework can describe complex magnetic potential energy surfaces, taking ferromagnetic iron as a paradigmatic challenging case. The training database includes total energies, forces, and stresses obtained from densityfunctional theory in the generalized-gradient approximation, and comprises approximately 150,000 local atomic environments, ranging from pristine and defected bulk configurations to surfaces and generalized stacking faults with different crystallographic orientations. We find the structural, vibrational and thermodynamic properties of the GAP model to be in excellent agreement with those obtained directly from first-principles electronic-structure calculations. There is good transferability to quantities, such as Peierls energy barriers, which are determined to a large extent by atomic configurations that were not part of the training set. We observe the benefit and the need of using highly converged electronic-structure calculations to sample a target potential energy surface. The end result is a systematically improvable potential that can achieve the same accuracy of densityfunctional theory calculations, but at a fraction of the computational cost.

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Section: G Gamma Surfaces and Dislocationssupporting

confidence: 72%

Achieving DFT accuracy with a machine-learning interatomic potential: Thermomechanics and defects in bcc ferromagnetic iron

Dragoni

Daff

Csänyi

et al. 2018

Phys. Rev. Materials

246

224

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“…[3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]), the main issue being to derive the dislocation mobility law from the atomic scale [18]. Among the different computational studies, calculations based on density-functional theory (DFT) have established some important features that were previously matter of debate in bcc transition metals, such as the nondegenerate dislocation core structure [6,10,17], the {110} glide plane [9], and the single-hump Peierls barrier [10,17,[19][20][21]. However, the main drawback of DFT-based methods applied to extended defects such as dislocations is the limited number of atoms that can be considered in the simulation cell, typically a few hundred.…”

Section: Introductionmentioning

confidence: 99%

First-principles prediction of kink-pair activation enthalpy on screw dislocations in bcc transition metals: V, Nb, Ta, Mo, W, and Fe

et al. 2015

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The atomistic study of kink pairs on screw dislocations in body-centered cubic (bcc) metals is challenging because interatomic potentials in bcc metals still lack accuracy and kink pairs require too many atoms to be modeled by first principles. Here, we circumvent this difficulty using a one-dimensional line tension model whose parameters, namely the line tension and Peierls barrier, are reachable to density functional theory calculations. The model parameterized in V, Nb, Ta, Mo, W, and Fe, is used to study the kink-pair activation enthalpy and spatial extension. Interestingly, we find that the atomistic line tension is more than twice the usual elastic estimates. The calculations also show interesting group tendencies with the line tension and kink-pair width larger in group V than in group VI elements. Finally, the present kink-pair activation energies are shown to compare qualitatively with experimental data and potential origins of quantitative discrepancies are discussed.

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“…The transition state is nearly in a "split" core configuration, which is same as that in the EAM potential but different from that in DFT. 8,31,32) In this calculation, there is no significant difference between the transition state at 0 K and that at 300 K. Figure 6 shows the free energy distribution of the transition state of each atom at 0 K and 300 K. The zero point of the free energy of each atom corresponds to a metastable state. Therefore, the increased free energy of each atom is a part of the Peierls barrier.…”

Section: Resultsmentioning

confidence: 99%

Peierls Barrier of Screw Dislocation in bcc Iron at Finite Temperature

Mori

2014

Mater. Trans.

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The Peierls barrier of a screw dislocation in body-centered cubic iron at finite temperature is investigated by using the free energy gradient method. By using the empirical potential, the Peierls barrier is shown to decrease from 11.7 to 6.9 meV per unit length of the Burgers vector with temperature increasing from 0 to 300 K. The entropy term of the Peierls barrier is estimated to be 0.19 k B , and the change of free energy, which is an entropic effect, is found to strongly depend on the local atomic configuration.

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Ab initio investigation of the Peierls potential of screw dislocations in bcc Fe and W

Cited by 123 publications

References 66 publications

Achieving DFT accuracy with a machine-learning interatomic potential: Thermomechanics and defects in bcc ferromagnetic iron

Achieving DFT accuracy with a machine-learning interatomic potential: Thermomechanics and defects in bcc ferromagnetic iron

First-principles prediction of kink-pair activation enthalpy on screw dislocations in bcc transition metals: V, Nb, Ta, Mo, W, and Fe

Peierls Barrier of Screw Dislocation in bcc Iron at Finite Temperature

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