Atomsk: A tool for manipulating and converting atomic data files

Hirel, Pierre

doi:10.1016/j.cpc.2015.07.012

Cited by 1,282 publications

(444 citation statements)

References 24 publications

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“…Initial configurations of screw dislocations are created by imposing in a perfect crystal an isotropic displacement field corresponding to a single screw dislocation line with b = [001] (Hirth and Lothe 1982) using the commandline program Atomsk (Hirel 2015). Then, relaxation of the atomic positions (as described above) yields a dislocation core configuration counting anisotropic effects.…”

Section: Designing and Analyzing Dissociated Screw And Edge Dislocatimentioning

confidence: 99%

Modeling defects and plasticity in MgSiO3 post-perovskite: Part 3—Screw and edge [001] dislocations

Goryaeva

Carrez

2017

Phys Chem Minerals

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Section: Designing and Analyzing Dissociated Screw And Edge Dislocatimentioning

confidence: 99%

Modeling defects and plasticity in MgSiO3 post-perovskite: Part 3—Screw and edge [001] dislocations

Goryaeva

Carrez

2017

Phys Chem Minerals

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“…The 〈110〉 pc dislocations belong to the easiest slip system in both materials [11], [6]. Atomic systems were constructed with Atomsk [12], and classical molecular statics and dynamics simulations were performed with LAMMPS [13]. Interatomic interactions in SrTiO 3 were modeled with the rigid-ion potential proposed by Thomas et al [14], and in MgSiO 3 with the one from Alfredsson et al [15].…”

mentioning

confidence: 99%

From glissile to sessile: Effect of temperature on 〈110〉 dislocations in perovskite materials

2016

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In perovskite-type strontium titanate (SrTiO 3 ) 〈110〉 dislocations, which are the main carriers of plastic flow at low temperature, lose their mobility as temperature increases, leading to brittle failure above 1050 K. We present theoretical evidence for a change in their core structure into a sessile, climb-dissociated configuration at high temperature. This mechanism is shown to operate in both SrTiO 3 and MgSiO 3 , indicating that it may be a general feature of perovskite-type materials. It follows that the activity of the 〈110〉 slip system depends critically on the strain rate-temperature couple, ð _ ε; TÞ.The discovery of the atypical mechanical behavior of strontium titanate (SrTiO 3 or STO) and its double ductile-brittle-ductile transition [1,2] has challenged our understanding of the plastic behavior of perovskite-type materials, and has since motivated several studies. A series of experiments [3,4] and simulations [5,6] have provided a good understanding of the ductile behavior of STO at low temperature and demonstrated its direct link with the glide of 〈110〉 dislocations. However it is still unclear why this mechanism becomes inactive at high temperature, leading to brittle failure above 1050 K. It was initially proposed that 〈110〉 dislocations become sessile by dissociating into two 〈100〉 dislocations, or because of a change of preferential slip plane [2]. Later it was proposed that 〈110〉 dislocations dissociate by climb at high temperature, into a configuration similar to the one observed in low-angle tilt grain boundaries [7,3]. Despite arguments in favor of the latter [8], there has been no direct evidence for this change of core structure, the mechanisms by which it operates are still unknown, and whether this transition is specific to STO or a general feature of perovskite-type materials remains an open question.In this work we investigate the effect of temperature on the core structure of individual [110] pc edge dislocations in two perovskitetype materials: the cubic strontium titanate, and the orthorhombic, high-pressure magnesium silicate MgSiO 3 which is the pure Mg endmember of bridgmanite [9], the main constituent of the Earth's lower mantle. In the following we consider MgSiO 3 under the hydrostatic pressure of 30 GPa, corresponding to a depth of ca. 700 km i.e. the uppermost lower mantle. Throughout this article crystal directions are given in the (pseudo-)cubic reference, noted with the subscript "pc", for easier comparison between the two materials (in MgSiO 3[110] pc = [100]; ½110 pc ¼ ½010 ; 2[001] pc = [001], see e.g. Ref.[10]). The 〈110〉 pc dislocations belong to the easiest slip system in both materials [11], [6]. Atomic systems were constructed with Atomsk [12], and classical molecular statics and dynamics simulations were performed with LAMMPS [13]. Interatomic interactions in SrTiO 3 were modeled with the rigid-ion potential proposed by Thomas et al. [14], and in MgSiO 3 with the one from Alfredsson et al. [15].The glide-dissociated core structures of [110] pc edge dislocation...

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“…Polycrystalline iron samples with different grain sizes were constructed following the Voronoi tessellation method [24], implemented within the Atomsk tool [25]. Five samples with average grain sizes, 58.8 \ D\141.2 Å , were built by randomly distributing seeds in a box having a size of 350 9 210 9 170 Å 3 .…”

Section: Computational Techniquementioning

confidence: 99%

Atomistic Insights on the Wear/Friction Behavior of Nanocrystalline Ferrite During Nanoscratching as Revealed by Molecular Dynamics

et al. 2017

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Using embedded atom method potential, extensive large-scale molecular dynamics (MD) simulations of nanoindentation/nanoscratching of nanocrystalline (nc) iron have been carried out to explore grain size dependence of wear response. MD results show no clear dependence of the frictional and normal forces on the grain size, and the single-crystal (sc) iron has higher frictional and normal force compared to nc-samples. For all samples, the dislocation-mediated mechanism is the primary cause of plastic deformation in both nanoindentation/nanoscratch. However, secondary cooperative mechanisms are varied significantly according to grain size. Pileup formation was observed in the front of and sideways of the tool, and they exhibit strong dependence on grain orientation rather than grain size. Tip size has significant impact on nanoscratch characteristics; both frictional and normal forces monotonically increase as tip radii increase, while the friction coefficient value drops by about 38%. Additionally, the increase in scratch depth leads to an increase in frictional and normal forces as well as friction coefficient. To elucidate the relevance of indentation/scratch results with mechanical properties, uniaxial tensile test was performed for nc-samples, and the result indicates the existence of both the regular and inverse Hall-Petch relations at critical grain size of 110.9 Å . The present results suggest that indentation/scratch hardness has no apparent correlation with the mechanical properties of the substrate, whereas the plastic deformation has.

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Atomsk: A tool for manipulating and converting atomic data files

Cited by 1,282 publications

References 24 publications

Modeling defects and plasticity in MgSiO3 post-perovskite: Part 3—Screw and edge [001] dislocations

Modeling defects and plasticity in MgSiO3 post-perovskite: Part 3—Screw and edge [001] dislocations

From glissile to sessile: Effect of temperature on 〈110〉 dislocations in perovskite materials

Atomistic Insights on the Wear/Friction Behavior of Nanocrystalline Ferrite During Nanoscratching as Revealed by Molecular Dynamics

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