Molecular dynamics simulations of shock-compressed single-crystal silicon

Mogni, Gabriele; Higginbotham, Andrew; Gaál-Nagy, Katalin; Park, Nigel; Wark, J. S.

doi:10.1103/physrevb.89.064104

Cited by 46 publications

(51 citation statements)

References 61 publications

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“…The sample was thermalised at 300K, before a fixed pressure (as opposed to the frequently used fixed velocity) piston was applied at position z = 0, launching a shock along the [001] crystallographic direction. As has been observed in previous work [21], these simulations display a phase transition to Imma at 31 GPa, with a significant mixed phase region visible. As such, they provide an ideal testbed for the LE formalism.…”

Section: Comparison Of Lagrangian Elastic Code With MD Simulationssupporting

confidence: 64%

“…As noted in the work of Mogni et al [21], the volume fraction, f V , is related to the number fraction, f N , by -…”

Section: Appendix a The Integration Routine -Algorithmic Formmentioning

confidence: 99%

“…It should be noted that in the published MD simulations [21], small rotations of each phase, about an axis perpendicular to the drive direction, are observed in the mixed-phase region, which further allow the region to accommodate the high shear stress. These rotations can not be taken into account in this 1D formulation.…”

Section: Comparison Of Lagrangian Elastic Code With MD Simulationsmentioning

confidence: 99%

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Simulations of the inelastic response of silicon to shock compression

Stubley

Higginbotham

Wark

2017

Computational Materials Science

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Recent experiments employing nanosecond white-light X-ray diffraction have demonstrated a complex response of pure, single crystal silicon to shock compression on ultra-fast timescales. We present here details of a Lagrangian code which tracks both longitudinal and transverse strains, and successfully reproduces the experimental response by incorporating a model of the shock-induced, yet kinetically inhibited, phase transition. This model is also shown to reproduce results of classical molecular dynamics simulations of shock compressed silicon.

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Section: Comparison Of Lagrangian Elastic Code With MD Simulationssupporting

confidence: 64%

“…As noted in the work of Mogni et al [21], the volume fraction, f V , is related to the number fraction, f N , by -…”

Section: Appendix a The Integration Routine -Algorithmic Formmentioning

confidence: 99%

Section: Comparison Of Lagrangian Elastic Code With MD Simulationsmentioning

confidence: 99%

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Simulations of the inelastic response of silicon to shock compression

Stubley

Higginbotham

Wark

2017

Computational Materials Science

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“…On the theoretical side, several classical simulations [16][17][18][19] have been devoted to study the shock-wave propagation in Si. Construction of a thermodynamically complete multi-phase equation of state, in order to accurately capture the many solid-solid and solid-liquid phase transitions exhibited by silicon, provides many challenges.…”

Section: Introductionmentioning

confidence: 99%

First-principles prediction of the softening of the silicon shock Hugoniot curve

Militzer

Collins

et al. 2016

Phys. Rev. B

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Shock compression of silicon (Si) under extremely high pressures (>100 Mbar) was investigated by using two first-principles methods of orbital-free molecular dynamics (OFMD) and path integral Monte Carlo (PIMC). While pressures from the two methods agree very well, PIMC predicts a second compression maximum because of 1s electron ionization that is absent in OFMD calculations since Thomas-Fermi-based theories lack shell structure. The Kohn-Sham density functional theory is used to calculate the equation of state (EOS) of warm dense silicon for low-pressure loadings (P < 100 Mbar).Combining these first-principles EOS results, the principal shock Hugoniot curve of 2 silicon for pressures varying from ~1 Mbar to above ~10 Gbar was derived. We find that silicon is ~20% or more softer than what was predicted by widely-used EOS models.Existing high-pressure experimental data (P ≈ 1 − 2 Mbar) seem to indicate this softening behavior of Si, which calls for future strong-shock experiments (P > 10 Mbar) to benchmark our results.

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“…In both the perfect and defective crystals we observe that the applied uniaxial strain produces shear stress which, above the onset of plasticity, nucleates a solid-solid phase transition which propagates along planar stacking faults. This shear stress driven partial phase transformation has been observed previously in MD simulations of germanium [31] and very recently in silicon [32]. The higher-density crystal is either a tetragonal (β-tin) or the closely-related orthorhombic (Imma) structure.…”

Section: Methodsmentioning

confidence: 52%

Enhanced densification under shock compression in porous silicon

2014

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Under shock compression, most porous materials exhibit lower densities for a given pressure than that of a full-dense sample of the same material. However, some porous materials exhibit an anomalous, or enhanced, densification under shock compression. We demonstrate a molecular mechanism that drives this behavior. We also present evidence from atomistic simulation that pure silicon belongs to this anomalous class of materials. Atomistic simulations indicate that local shear strain in the neighborhood of collapsing pores nucleates a local solid-solid phase transformation even when bulk pressures are below the thermodynamic phase transformation pressure. This metastable, local, and partial, solid-solid phase transformation, which accounts for the enhanced densification in silicon, is driven by the local stress state near the void, not equilibrium thermodynamics. This mechanism may also explain the phenomenon in other covalently bonded materials.

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Molecular dynamics simulations of shock-compressed single-crystal silicon

Cited by 46 publications

References 61 publications

Simulations of the inelastic response of silicon to shock compression

Simulations of the inelastic response of silicon to shock compression

First-principles prediction of the softening of the silicon shock Hugoniot curve

Enhanced densification under shock compression in porous silicon

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