Parametrization of a reactive force field for aluminum hydride

Ojwang, J. G. O.; Santen, Rutger A. van; Kramer, Gert Jan; Duin, Adri C. T. van; Goddard, William A.

doi:10.1063/1.3182853

Cited by 43 publications

(38 citation statements)

References 51 publications

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“…, and bond information from Al-H, 58 and crystal parameters from Al-C, 60 and Al-N. 61 The modified ReaxFF provides a good descriptions of crystal constants, bulk modulus, cohesive energies and EOS curves of various crystal phases and a large number of cluster conformations, thanks to the global optimization strategy employed. 40 The 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 §N.…”

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confidence: 99%

Thermodynamic Simulation of the RDX–Aluminum Interface Using ReaxFF Molecular Dynamics

Wang

Peng

Pang³

et al. 2017

J. Phys. Chem. C

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Abstract:We use reactive molecular dynamics (RMD) simulations to study the interface between cyclotrimethylene trinitramine (RDX) and Aluminum (Al) with different oxide layers to elucidate the effect of nano-sized Al on thermal decomposition of RDX. A published ReaxFF force field for C/H/N/O elements was retrained to incorporate Al interactions, and then used in RMD simulations to characterize compound energetic materials. We find that the predicted adsorption energies for RDX on the Al (111) for RDX(210)/Al 2 O 3 (0001) provide a more accurate description. We conclude that the origin of these differences in dynamic behavior is due to the variations in the oxide layer morphologies.

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confidence: 99%

Thermodynamic Simulation of the RDX–Aluminum Interface Using ReaxFF Molecular Dynamics

Wang

Peng

Pang³

et al. 2017

J. Phys. Chem. C

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“…The ReaxFF force field versions used in the simulations have been based on earlier published versions of Al/O [37,38], Al/H [39], O/H [40] and Al/O/H [41] force fields (Table 1).…”

Section: Methodsmentioning

confidence: 99%

α-Al2O3 nanoslab fracture and fatigue behavior

Verners

Psofogiannakis

Duin

2015

Computational Materials Science

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a b s t r a c tStrain rate effects and cyclic loading behavior, relevant for fatigue initiation processes, of single crystalline a-Al 2 O 3 nanoslab structures in vacuum have been characterized and compared under finite temperature dynamic loading and incremental static loading conditions by reactive molecular dynamics and ionic relaxation simulations, respectively. Different failure mechanisms for each loading case are observed and compared in view of known applicable material failure mechanisms. In particular, structure size effects along with unit cell and bulk defect distribution based mechanisms are considered. The effects of lateral pre-strain are assessed. Conclusions are drawn regarding conditions which could lead to low cycle failure of the material.The results indicate that finite temperature and strain rate result in lower failure strains, as compared to static relaxation calculations, however low strength enhancement of ductility with kinematic strain hardening upon repeated loading may occur. We suggest that the latter facilitates a shakedown mechanism. Positive pre-straining results in increased stress triaxiality (hydrostatic vs. equivalent stress), which significantly reduces crack healing probability, due to single sharp crack propagation. Instead, volume pre-relaxation results in multiple crack branching and/or amorphous band formation, which facilitates crack healing and deformation induced transition to purely elastic response (shakedown) possibility. Amorphization, which manifests as small strain plasticity enhancement, is found to occur ahead of propagating cracks due to multiple dislocation mechanism as a low energy barrier partially reversible low density phase transition, both at static and finite temperature/strain rate conditions. The observed property changes and phase change related defect healing mechanisms have been investigated further by bulk unit cell simulations and validated against DFT calculations.

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“…It has already been shown that ReaxFF provides a reliable description of the bulk properties, surface, and cluster properties of both aluminum 15 and aluminum hydride. 1 During the MD simulation atomic charges were updated per every iteration. This dynamical charge transfer allowed for fluctuations of atomic charges depending on the coordination of the atom.…”

Section: A Theoretical Methodsmentioning

confidence: 99%

“…1 That is, the alane molecules first of all agglomerate/oligomerize before the desorption of molecular hydrogen occurs. In the light of these results, one might wonder if the same scenario ͑agglomeration͒ is mirrored in the condensed phase.…”

Section: Introductionmentioning

confidence: 99%

“…We have chosen to study the interactions of alanes on Al͑111͒ surface for the following four reasons: ͑i͒ we already have a well parametrized force field that aptly describes aluminum and aluminum hydride systems, 1 ͑ii͒ we have reactions of alanes in the gas phase and so it is worthwhile to make a comparison between the gas phase dynamics and surface reactions, 1 ͑iii͒ alanes are believed to be the ubiquitous facilitators of mass transport of aluminum atoms during the thermal decomposition of NaAlH 4 , which is a potential hydrogen storage material, [2][3][4][5] and ͑iv͒ alanes also take part on decomposition of AlH 3 , another important material for hydrogen storage.…”

Section: Introductionmentioning

confidence: 99%

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Multiscale modeling of interaction of alane clusters on Al(111) surfaces: A reactive force field and infrared absorption spectroscopy approach

Ojwang

Chaudhuri

Duin

et al. 2010

The Journal of Chemical Physics

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We have used reactive force field ͑ReaxFF͒ to investigate the mechanism of interaction of alanes on Al͑111͒ surface. Our simulations show that, on the Al͑111͒ surface, alanes oligomerize into larger alanes. In addition, from our simulations, adsorption of atomic hydrogen on Al͑111͒ surface leads to the formation of alanes via H-induced etching of aluminum atoms from the surface. The alanes then agglomerate at the step edges forming stringlike conformations. The identification of these stringlike intermediates as a precursor to the bulk hydride phase allows us to explain the loss of resolution in surface IR experiments with increasing hydrogen coverage on single crystal Al͑111͒ surface. This is in excellent agreement with the experimental works of Go et al. ͓E. Go, K. Thuermer, and J. E. Reutt-Robey, Surf. Sci. 437, 377 ͑1999͔͒. The mobility of alanes molecules has been studied using molecular dynamics and it is found that the migration energy barrier of Al 2 H 6 is 2.99 kcal/mol while the prefactor is D 0 = 2.82ϫ 10 −3 cm 2 / s. We further investigated the interaction between an alane and an aluminum vacancy using classical molecular dynamics simulations. We found that a vacancy acts as a trap for alane, and eventually fractionates/annihilates it. These results show that ReaxFF can be used, in conjunction with ab initio methods, to study complex reactions on surfaces at both ambient and elevated temperature conditions.

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Parametrization of a reactive force field for aluminum hydride

Cited by 43 publications

References 51 publications

Thermodynamic Simulation of the RDX–Aluminum Interface Using ReaxFF Molecular Dynamics

Thermodynamic Simulation of the RDX–Aluminum Interface Using ReaxFF Molecular Dynamics

α-Al2O3 nanoslab fracture and fatigue behavior

Multiscale modeling of interaction of alane clusters on Al(111) surfaces: A reactive force field and infrared absorption spectroscopy approach

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