X. He

The ABINIT project: Impact, environment and recent developments

X. Gonze, B. Amadon, G. Antonius, F. Arnardi, L. Baguet, J.-M. Beuken, J. Bieder, F. Bottin, J. Bouchet, E. Bousquet, N. Brouwer, F. Bruneval, G. Brunin, T. Cavignac, J.-B. Charraud, W. Chen, M. Côté, S. Cottenier, J. Denier, G. Geneste, P. Ghosez, M. Giantomassi, Y. Gillet, O. Gingras, D.R. Hamann, G. Hautier, X. He, N. Helbig, N.A.W. Holzwarth, Y. Jia, F. Jollet, W. Lafargue-Dit-Hauret, K. Lejaeghere, M.A.L. Marques, A. Martin, C. Martins, H.P.C. Miranda, F. Naccarato, K. Persson, G. Petretto, V. Planes, Y. Pouillon, S. Prokhorenko, F. Ricci, G.-M. Rignanese, A.H. Romero, M.M. Schmitt, M. Torrent, M.J. van Setten, B. Van Troeye, M.J. Verstraete, G. Zérah, J.W. Zwanziger
Computer Physics Communications
248, 107042
2020
A1

Abstract 

Abinit is a material- and nanostructure-oriented package that implements density-functional theory (DFT) and many-body perturbation theory (MBPT) to find, from first principles, numerous properties including total energy, electronic structure, vibrational and thermodynamic properties, different dielectric and non-linear optical properties, and related spectra. In the special issue to celebrate the 40th anniversary of CPC, published in 2009, a detailed account of Abinit was included [Gonze et al. (2009)], and has been amply cited. The present article comes as a follow-up to this 2009 publication. It includes an analysis of the impact that Abinit has had, through for example the bibliometric indicators of the 2009 publication. Links with several other computational materials science projects are described. This article also covers the new capabilities of Abinit that have been implemented during the last three years, complementing a recent update of the 2009 article published in 2016. Physical and technical developments inside the abinit application are covered, as well as developments provided with the Abinit package, such as the multibinit and a-tdep projects, and related Abinit organization developments such as AbiPy . The new developments are described with relevant references, input variables, tests, and tutorials.

Interaction of carbon-vacancy complex with minor alloying elements of ferritic steels

A. Bakaev, D. Terentyev, X. He, E. Zhurkin, D. Van Neck
Journal of Nuclear Materials
451 (1-3), 82-87
2014
A1

Abstract 

Interstitial carbon, dissolved in bcc matrix of ferritic steels, plays an important role in the evolution of radiation-induced microstructure since it exhibits strong interaction with vacancies. Frequent formation and break-up of carbon-vacancy pairs, occurring in the course of irradiation, affect both kinetics of the accumulation of point defect clusters and carbon spatial distribution. The interaction of typical alloying elements (Mn, Ni, Cu, Si, Cr and P) in ferritic steels used as structural materials in nuclear reactors with a carbon-vacancy complex is analyzed using ab initio techniques. It is found that all the considered solutes form stable triple clusters resulting in the increase of the total binding energy by 0.2-0.3 eV. As a result of the formation of energetically favourable solute-carbon-vacancy triplets, the dissociation energy for vacancy/carbon emission is also increased by similar to 0.2-0.3 eV, suggesting that the solutes enhance thermal stability of carbon-vacancy complex. Association of carbon-vacancy pairs with multiple solute clusters is found to be favorable for Ni, Cu and P. The energetic stability of solute(s)-carbon-vacancy complexes was rationalized on the basis of pairwise interaction data and by analyzing the variation of local magnetic moments on atoms constituting the clusters. (C) 2014 Elsevier B.V. All rights reserved.

DOI 

10.1016/j.jnucmat.2014.03.031

Hardening due to dislocation loop damage in RPV model alloys: role of Mn segregation

D. Terentyev, X. He, G. Bonny, A. Bakaev, E. Zhurkin, L. Malerba
Journal of Nuclear Materials
457, 173–181
2015
A1

Abstract 

The exact nature of the radiation defects causing hardening in reactor vessel pressure steels at high doses is not yet clearly determined. While generally it is attributed to solute-rich clusters (precipitates) and point defects clusters (matrix damage), recent fine-scale experiments and atomistic simulations suggest that solute rich clusters, mainly containing Mn, Ni and Cu, might be the result of the segregation of these elements to small dislocation loops (heterogeneous nucleation), so that the distinction between precipitates and matrix damage becomes blurred. Here, we perform an atomistic study to investigate the interaction of a0/2〈1 1 1〉 dislocation loops with moving dislocations and specifically address the effect of solute segregation on the loop’s strength and interaction mechanism, focusing in particular on Mn, alone or with other crucial solute elements such as Cu and Ni. It is found that the enrichment of Mn in the core of dislocation loops causes significant increase of the unpinning stress, especially for small, invisible ones. At the same time, the solute segregation at the dislocation loops enhances their resistance against absorption by moving dislocations.

Synergetic Effects of Mn and Si in the Interaction with Point Defects in bcc Fe

A. Bakaev, D. Terentyev, X. He, D. Van Neck
Journal of Nuclear Materials
455 (1-3), 5-9
2014
A1

Abstract 

The interaction of Mn, Si and Cr with a vacancy and self-interstitial defects in BCC Fe has been analyzed using ab initio calculations. While the interaction of the considered solute clusters with a single vacancy is linearly additive, there is a considerable synergetic effect in the case of self-interstitial atoms, found to bind strongly with Mn–Si pairs. The latter therefore act as deep trapping configurations for self-interstitials. At the same time, the presence of the point defects nearby weakly attractive Mn–Si pairs significantly enhances the solute–solute binding. The revealed effects are rationalized on the basis of charge density and local magnetic moment distributions.

Energetics of radiation defects in Fe-based austenitic alloys: Atomic scale study

A. Bakaev, D. Terentyev, X. He, E. Zhurkin
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
303, 33–36
2013
A1

Abstract 

Energetics of typical radiation defects observed in austenitic stainless steel of 304L type has been characterized in the model FeNi10Cr20 alloy by means of atomistic simulations employing a set of interatomic potentials specially derived to reproduce main features of 304L steel. The following defects have been considered: dislocation loops of both interstitial and vacancy nature, stacking fault tetrahedron, perfect loops and voids. The formation energy of these defects has been calculated at 0 K and the obtained results have been compared with the prediction of the elasticity theory. A good agreement has been found in all the cases except for the hexagonal Frank loop, whose sides have splitted into 1/6〈1 1 2〉 partial dislocations, thus lowering the total formation energy. High temperature annealing, performed using molecular dynamics simulations, has proven that the considered defects are thermally stable in the temperature range 300–1200 K.

Segregation of Cr at tilt grain boundaries in Fe-Cr alloys: A Metropolis Monte Carlo study

D. Terentyev, X. He, E. Zhurkin, A. Bakaev
Journal of Nuclear Materials
408, 161–170
2011
A1

Abstract 

In this work, the Metropolis Monte Carlo (MMC) method employing the isothermal–isobaric statistical ensemble is applied to investigate segregation at grain boundaries in bcc Fe–Cr alloys with varying Cr content from 5 to 14 at.%. Several different 〈1 1 0〉 tilt grain boundaries, namely: Σ19{3 3 1}, Σ9{2 2 1}, Σ3{1 1 1}, Σ3{1 1 2}, Σ11{1 1 3}, Σ9{1 1 4} with misorientation angle varying in the range 26–141° were considered. Systematic MMC simulations were performed employing a two band empirical many-body potential in the temperature range 300–900 K. It was found that the binding energy of substitutional Cr to the GB core is essentially determined by the structure of the GB interface and varies in the range 0.05–0.35 eV. At this, the binding energy increases with the GB excess volume. MMC simulations revealed that either a local atomic rearrangement or segregation of Cr at the considered GBs occurs depending on the combination of temperature, alloy composition and GB structure. Influence of temperature and GB structure on the local atomic rearrangement and precipitation of α′ particles is demonstrated.

Abonneren op RSS - X. He