Simulating picosecond x-ray diffraction from shocked crystals using post-processing molecular dynamics calculations

Kimminau, Giles; Nagler, Bob; Higginbotham, Andrew; Murphy, William J.; Park, Nigel; Hawreliak, J.; Kadau, Kai; Germann, Timothy C.; Bringa, Eduardo M.; Kalantar, D. H.; Lorenzana, H. E.; Remington, B. A.; Wark, J. S.

doi:10.1088/0953-8984/20/50/505203

Cited by 25 publications

(19 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In order to relax the requirements on computational power, we present a method of simulating the response of a fibre textured target by manipulation of a single crystal simulation. We do this by first performing a 3D Fourier Transform (FT) of the computed electron density of the single crystal 53 . This provides us with a momentum space representation of the lattice which describes the allowed scattering vectors for diffraction.…”

Section: Molecular Dynamics Simulationsmentioning

confidence: 99%

Simulations of in situ x-ray diffraction from uniaxially compressed highly textured polycrystalline targets

McGonegle

Milathianaki

Remington

et al. 2015

Journal of Applied Physics

Self Cite

View full text Add to dashboard Cite

A growing number of shock compression experiments, especially those involving laser compression, are taking advantage of in situ x-ray diffraction as a tool to interrogate structure and microstructure evolution. Although these experiments are becoming increasingly sophisticated, there has been little work on exploiting the textured nature of polycrystalline targets to gain information on sample response. Here, we describe how to generate simulated x-ray diffraction patterns from materials with an arbitrary texture function subject to a general deformation gradient. We will present simulations of Debye-Scherrer x-ray diffraction from highly textured polycrystalline targets that have been subjected to uniaxial compression, as may occur under planar shock conditions. In particular, we study samples with a fibre texture, and find that the azimuthal dependence of the diffraction patterns contains information that, in principle, affords discrimination between a number of similar shock-deformation mechanisms. For certain cases we compare our method with results obtained by taking the Fourier Transform of the atomic positions calculated by classical molecular dynamics simulations. Illustrative results are presented for the shock-induced α-ǫ phase transition in iron, the α-ω transition in titanium and deformation due to twinning in tantalum that is initially preferentially textured along [001] and [011]. The simulations are relevant to experiments that can now be performed using 4th generation light sources, where single-shot x-ray diffraction patterns from crystals compressed via laser-ablation can be obtained on timescales shorter than a phonon period.

show abstract

Section: Molecular Dynamics Simulationsmentioning

confidence: 99%

Simulations of in situ x-ray diffraction from uniaxially compressed highly textured polycrystalline targets

McGonegle

Milathianaki

Remington

et al. 2015

Journal of Applied Physics

Self Cite

View full text Add to dashboard Cite

show abstract

“…4 simulated powder diffraction data. These were obtained by calculating the Fourier transform of the atomic coordinates, allowing interrogation of reciprocal space equivalent to that accessed in Debye-Scherrer diffraction geometries [33]. In Fig.…”

Section: Fig 3 (Color Online)mentioning

confidence: 99%

Shock waves in polycrystalline iron: Plasticity and phase transitions

et al. 2014

Self Cite

View full text Add to dashboard Cite

At a pressure of around 13 GPa iron undergoes a structural phase transition from the bcc to the hexagonal close-packed phase. Atomistic simulations have provided important insights into this transition. However, while experiments in polycrystals show clear evidence that the αtransition is preceded by plasticity, simulations up to now could not detect any plastic activity occurring before the phase change. Here we study shock waves in polycrystalline Fe using an interatomic potential which incorporates the αtransition faithfully. Our simulations show that the phase transformation is preceded by dislocation generation at grain boundaries, giving a three-wave profile. The αtransformation pressure is much higher than the equilibrium transformation pressure but decreases slightly with increasing loading ramp time (decreasing strain rate). The transformed phase is mostly composed of hcp grains with large defect density. Simulated x-ray diffraction displays clear evidence for this hcp phase, with powder-diffraction-type patterns as they would be seen using current experimental setups.

show abstract

“…The Figure 3. XRD patterns, computed [22,23] (red) and experimental (blue). Note that in calculations the atomic form factor is assumed to be independent of scattering angle and set equal to unity.…”

mentioning

confidence: 99%

Quenching of bcc-Fe from high to room temperature at high-pressure conditions: a molecular dynamics simulation

et al. 2009

View full text Add to dashboard Cite

Simulating picosecond x-ray diffraction from shocked crystals using post-processing molecular dynamics calculations

Cited by 25 publications

References 30 publications

Simulations of in situ x-ray diffraction from uniaxially compressed highly textured polycrystalline targets

Simulations of in situ x-ray diffraction from uniaxially compressed highly textured polycrystalline targets

Shock waves in polycrystalline iron: Plasticity and phase transitions

Quenching of bcc-Fe from high to room temperature at high-pressure conditions: a molecular dynamics simulation

Contact Info

Product

Resources

About