Structural Relaxation Made Simple

Bitzek, Erik; Koskinen, Pekka; Gähler, Franz; Moseler, Michael; Gumbsch, Peter

doi:10.1103/physrevlett.97.170201

Cited by 1,538 publications

(1,182 citation statements)

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“…All our structural relaxations were performed under constant stress using the Fast Inertial Relaxation Engine (FIRE). 19,20 For this purpose, we had to modify the algorithm accordingly (see Appendix A). Every 10 steps, we cycled through non-magnetic, ferromagnetic, antiferromagnetic-checkerboard, stripe-type antiferromagnetic (along unit cell axis a) and stripe-type antiferromagnetic (along unit cell axis b) spin configurations, and then we continued the relaxation with the lowest energy spin configuration.…”

Section: Methodsmentioning

confidence: 99%

In-plane uniaxial stress effects on the structural and electronic properties of BaFe2As2and CaFe2As
Tomić
¹
,
Jeschke
²
,
Fernandes
³

et al. 2013
Phys. Rev. B
28
5
23
1
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Starting from the orthorhombic magnetically ordered phase, we investigate the effects of uniaxial tensile and compressive stresses along a, b, and the diagonal a+b directions in BaFe2As2 and CaFe2As2 in the framework of ab initio density functional theory (DFT) and a phenomonological Ginzburg-Landau model. While -contrary to the application of hydrostatic or c-axis uniaxial pressure-both systems remain in the orthorhombic phase with a pressure-dependent nonzero magnetic moment, we observe a sign-changing jump in the orthorhombicity at a critical uniaxial pressure, accompanied by a reversal of the orbital occupancy and a switch between the ferromagnetic and antiferromagnetic directions. Our Ginzburg-Landau analysis reveals that this behavior is a direct consequence of the competition between the intrinsic magneto-elastic coupling of the system and the applied compressive stress, which helps the system to overcome the energy barrier between the two possible magneto-elastic ground states. Our results shed light on the mechanisms involved in the detwinning process of an orthorhombic iron-pnictide crystal and on the changes in the magnetic properties of a system under uniaxial stress.

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Section: Methodsmentioning

confidence: 99%

In-plane uniaxial stress effects on the structural and electronic properties of BaFe2As2and CaFe2As
Tomić
¹
,
Jeschke
²
,
Fernandes
³

et al. 2013
Phys. Rev. B
28
5
23
1
View full text Add to dashboard Cite

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“…Prior to nanoscratching, the as-created nt Cu samples are first relaxed to their equilibrium configurations by the following procedure: The atoms in the samples are first relaxed to their minimum energy configurations using the FIRE (fast inertia relaxation engine) algorithm. 25 Then the samples are heated up to 30 K by dynamic MD simulation using the Nose-Hoover thermostat for 40 ps in the isothermal-isobaric NPT ensemble. The equilibrated Cu samples are then subjected to nanoscratching using a spherical diamond probe with a radius of 4 nm in the microcanonical NVE ensemble.…”

Section: Simulation Methodsmentioning

confidence: 99%

Twin boundary spacing-dependent friction in nanotwinned copper

et al. 2012

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The deformation mechanisms of nanotwinned Cu subjected to nanoscratching are investigated by means of molecular dynamics simulations. Scratching simulations on nanotwinned single-crystalline Cu with the twin planes parallel and perpendicular to the scratching direction are performed. Since the detwinning mechanism is completely suppressed in the former case, no apparent correlation between frictional coefficient and the twin spacing is observed. In samples where the twin planes are perpendicular to the scratching direction, the friction increases as the twin spacing decreases, and then decreases as the twin spacings become even smaller. It results from the competitive plastic deformation between the inclined dislocations and the detwinning mechanism. Subsequent simulations for nanotwinned polycrystalline Cu unveil that in addition to the grainboundary-associated deformation mechanism, dislocation-mediated detwinning plays a significant role in the plastic deformation of nanotwinned Cu. The twin boundary spacing in turn affects nanotwinned materials to resist scratching via plastic deformation. We demonstrate via the nanoscratching tests that there exists a critical twin boundary spacing for which the friction coefficient is maximized and that this transition results from the competing deformation mechanisms in those nanotwinned materials.

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“…We study a mixture of particles with radii distributed uniformly between a and 1.4a all with the same mass m. The units of length, mass, and energy are a, m, and . The initial particle configurations were prepared by randomly placing the particle centers within the simulation box and then quenching to zero temperature using a fast inertial relaxation engine algorithm [21] to relax the total energy. The particle packing fraction was adjusted to yield the desired pressure p, as in Ref.…”

mentioning

confidence: 99%

Period proliferation in periodic states in cyclically sheared jammed solids

2017

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Athermal disordered systems can exhibit a remarkable response to an applied oscillatory shear: after a relatively few shearing cycles, the system falls into a configuration that had already been visited in a previous cycle. After this point the system repeats its dynamics periodically despite undergoing many particle rearrangements during each cycle. We study the behavior of orbits as we approach the jamming point in simulations of jammed particles subject to oscillatory shear at fixed pressure and zero temperature. As the pressure is lowered, we find that it becomes more common for the system to find periodic states where it takes multiple cycles before returning to a previously visited state. Thus, there is a proliferation of longer periods as the jamming point is approached.Keywords: cyclic shearing, reversibility, memory, absorbing-state phase transition, jammingOscillatory sheared athermal particle packings or suspensions can fall into periodic "absorbing states" [1] in which the system returns to a configuration previously visited during the shearing process at the same point in the cycle. Once it returns to that configuration, the dynamics repeats itself indefinitely. At low densities in the absorbing state, the particles follow the flow without ever making contact with one another so that the system moves back and forth along a flat direction in the energy landscape [2][3][4], and particles return to their original positions after a single shear cycle: T = 1. As the strain amplitude γ t increases beyond some value γ * t , particles can no longer avoid each other and the system undergoes a dynamical "absorbing state" transition from the absorbing phase to a phase in which the system continually visits new configurations. Models [3,[5][6][7][8] have linked this transition to variants of directed percolation [8][9][10], which represents a broad class of non-equilibrium phase transitions [1].Athermal glasses such as Lennard-Jones glasses, by contrast, have an extensive entropy of energy minima that are not flat [11][12][13]. At very small strain amplitudes, they exhibit elastic behavior in which they explore different configurations within the same energy minimum. As γ t increases so that the system can explore more than one minimum, one might expect the system to meander indefinitely around a hopelessly intricate energy landscape as the system is driven in an oscillatory fashion. Yet, remarkably, these systems can fall into absorbing states-they can find their way back to previously visited energy minima even as they undergo multiple particle rearrangements. Thus these systems explore many such minima [14-17] over and over again. Finally, when γ t is increased to γ * t , the system undergoes an absorbing state transition to a phase in which the system never returns to previously visited minima.In this paper we investigate the fate of absorbing states in packings of jammed spheres that can be tuned to the jamming transition, where the system loses rigidity [18,19]. Far above this transition, absorbing states...

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Structural Relaxation Made Simple

Cited by 1,538 publications

References 16 publications

In-plane uniaxial stress effects on the structural and electronic properties of BaFe2As2and CaFe2As
Tomić
¹
,
Jeschke
²
,
Fernandes
³

et al. 2013
Phys. Rev. B
28
5
23
1
View full text Add to dashboard Cite

In-plane uniaxial stress effects on the structural and electronic properties of BaFe2As2and CaFe2As
Tomić
¹
,
Jeschke
²
,
Fernandes
³

et al. 2013
Phys. Rev. B
28
5
23
1
View full text Add to dashboard Cite

Twin boundary spacing-dependent friction in nanotwinned copper

Period proliferation in periodic states in cyclically sheared jammed solids

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Structural Relaxation Made Simple

Cited by 1,538 publications

References 16 publications

In-plane uniaxial stress effects on the structural and electronic properties of BaFe2As2and CaFe2AsTomić1, Jeschke2, Fernandes3 et al. 2013Phys. Rev. B285231View full textAdd to dashboardCite

In-plane uniaxial stress effects on the structural and electronic properties of BaFe2As2and CaFe2AsTomić1, Jeschke2, Fernandes3 et al. 2013Phys. Rev. B285231View full textAdd to dashboardCite

Twin boundary spacing-dependent friction in nanotwinned copper

Period proliferation in periodic states in cyclically sheared jammed solids

Contact Info

Product

Resources

About

In-plane uniaxial stress effects on the structural and electronic properties of BaFe2As2and CaFe2As
Tomić
¹
,
Jeschke
²
,
Fernandes
³

et al. 2013
Phys. Rev. B
28
5
23
1
View full text Add to dashboard Cite

In-plane uniaxial stress effects on the structural and electronic properties of BaFe2As2and CaFe2As
Tomić
¹
,
Jeschke
²
,
Fernandes
³

et al. 2013
Phys. Rev. B
28
5
23
1
View full text Add to dashboard Cite