Threshold Crack Speed Controls Dynamical Fracture of Silicon Single Crystals

Buehler, Markus J.; Tang, Harvey; Duin, Adri C. T. van; Goddard, William A.

doi:10.1103/physrevlett.99.165502

Cited by 138 publications

(136 citation statements)

References 31 publications

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“…Since all intended applications were at temperatures well above the water boiling point, this was not a major development concern. In 2009, efforts were initiated to redevelop ReaxFF for aqueous chemistry, and it became clear that the 2008-C/H/O combustion force field, which at that time was already extended to a significant range of metal oxide (Me = V/Bi/Mo/Nb/Si) materials and catalysts, [27][28][29][30][31] could not be parameterised to treat liquid water without changing general-ReaxFF and atom-specific parameters. As such, the decision was made to initiate a new branch-the aqueousbranch-that employs the same functional form as the 2008-C/H/O description, but with different O/H atom and bond parameters.…”

Section: Current Reaxff Methodologymentioning

confidence: 99%

The ReaxFF reactive force-field: development, applications and future directions

et al. 2016

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The reactive force-field (ReaxFF) interatomic potential is a powerful computational tool for exploring, developing and optimizing material properties. Methods based on the principles of quantum mechanics (QM), while offering valuable theoretical guidance at the electronic level, are often too computationally intense for simulations that consider the full dynamic evolution of a system. Alternatively, empirical interatomic potentials that are based on classical principles require significantly fewer computational resources, which enables simulations to better describe dynamic processes over longer timeframes and on larger scales. Such methods, however, typically require a predefined connectivity between atoms, precluding simulations that involve reactive events. The ReaxFF method was developed to help bridge this gap. Approaching the gap from the classical side, ReaxFF casts the empirical interatomic potential within a bond-order formalism, thus implicitly describing chemical bonding without expensive QM calculations. This article provides an overview of the development, application, and future directions of the ReaxFF method. INTRODUCTIONAtomistic-scale computational techniques provide a powerful means for exploring, developing and optimizing promising properties of novel materials. Simulation methods based on quantum mechanics (QM) have grown in popularity over recent decades due to the development of user-friendly software packages making QM level calculations widely accessible. Such availability has proved particularly relevant to material design, where QM frequently serves as a theoretical guide and screening tool. Unfortunately, the computational cost inherent to QM level calculations severely limits simulation scales. This limitation often excludes QM methods from considering the dynamic evolution of a system, thus hampering our theoretical understanding of key factors affecting the overall behaviour of a material. To alleviate this issue, QM structure and energy data are used to train empirical force fields that require significantly fewer computational resources, thereby enabling simulations to better describe dynamic processes. Such empirical methods, including reactive force-field (ReaxFF), 1 trade accuracy for lower computational expense, making it possible to reach simulation scales that are orders of magnitude beyond what is tractable for QM.Atomistic force-field methods utilise empirically determined interatomic potentials to calculate system energy as a function of atomic positions. Classical approximations are well suited for nonreactive interactions, such as angle-strain represented by harmonic potentials, dispersion represented by van der Waals potentials and Coulombic interactions represented by various polarisation schemes. However, such descriptions are inadequate for modelling changes in atom connectivity (i.e., for modelling chemical reactions as bonds break and form). This motivates the

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Section: Current Reaxff Methodologymentioning

confidence: 99%

The ReaxFF reactive force-field: development, applications and future directions

et al. 2016

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“…In this work, we use a parameterization of ReaxFF extended to the simulation of silica (Duin et al 2003;Chenoweth et al 2005) which is suitable for the two materials we consider in this work. Previous studies on the fracture of silicon have used ReaxFF successfully (Buehler et al , 2007, and the potential formulation does not seem to exhibit spurious features that would strongly affect the fracture behavior such as the force peak in the REBO reactive potential (Belytschko et al 2002). In our simulations, the fracture behavior simulated with reaxFF is consistent with the expected materials behaviors: brittle fracture but without cleavage for the silica (Swiler 1994;Swiler et al 1995), and chain elongation and scission of the nanoporous carbon (Rottler 2009).…”

Section: Simulation Detailsmentioning

confidence: 99%

Capturing material toughness by molecular simulation: accounting for large yielding effects and limits

et al. 2015

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The inherent computational cost of molecular simulations limits their use to the study of nanometric systems with potentially strong size effects. In the case of fracture mechanics, size effects due to yielding at the crack tip can affect strongly the mechanical response of small systems. In this paper we consider two examples: a silica crystal for which yielding is limited to a few atoms at the crack tip, and a nanoporous polymer for which the process zone is about one order of magnitude larger. We perform molecular simulations of fracture of those materials and investigate in particular the system and crack size effects. The simulated systems are periodic with an initial crack. Quasi-static loading is achieved by increasing the system size in the direction orthogonal to the crack while maintaining a constant temperature. As expected, the behaviors of the two materials are significantly different. We show that the behavior of the silica crystal is reasonably well described by the classical framework of linear elastic fracture mechanics (LEFM). Therefore, one can easily upscale engineering fracture properties from molecular simulation results. In contrast, LEFM fails capturing the behavior of the polymer and we propose an alternative analysis based on cohesive crack zone models. We show that with a linear decreasing cohesive law, this alternative approach captures well the behavior of the polymer. Using this cohesive law, one can anticipate the mechanical behavior at larger scale and assess engineering fracture properties. Thus, despite the large yielding of the polymer at the scale of the molecular simulation, the cohesive zone analysis offers a proper upscaling methodology.

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“…For eight different iron potentials, they concluded that there was too much variation of unstable stacking fault energies and the resulting K IC variation for emitting dislocations of 40% was far too large. However, use of other material simulation techniques, [194][195][196][197] mostly theoretical and applied mechanics, have produced some success, but are not often compared to the atomistic fundamentals. To achieve a more complete understanding of DBTs over multiple modeling scales, detailed in situ experiments measuring plastic and fracture properties of multiple materials are needed.…”

Section: Future Nanomechanical Approaches To Brittleness Transitionsmentioning

confidence: 99%

Review Article: Case studies in future trends of computational and experimental nanomechanics

Tadmor

Kysar

Zimmerman

et al. 2017

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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With rapidly increasing numbers of studies of new and exotic material uses for perovskites and quasicrystals, these demand newer instrumentation and simulation developments to resolve the revealed complexities. One such set of observational mechanics at the nanoscale is presented here for somewhat simpler material systems. The expectation is that these approaches will assist those materials scientists and physicists needing to verify atomistic potentials appropriate to the nanomechanical understanding of increasingly complex solids. The five following segments from nine University, National and Industrial Laboratories both review and forecast where some of the important approaches will allow a confirming of how in situ mechanics and nanometric visualization might unravel complex phenomena. These address two-dimensional structures, temporal models for the nanoscale, atomistic and multiscale friction fundamentals, nanoparticle surfaces and interfaces a) Electronic

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Threshold Crack Speed Controls Dynamical Fracture of Silicon Single Crystals

Cited by 138 publications

References 31 publications

The ReaxFF reactive force-field: development, applications and future directions

The ReaxFF reactive force-field: development, applications and future directions

Capturing material toughness by molecular simulation: accounting for large yielding effects and limits

Review Article: Case studies in future trends of computational and experimental nanomechanics

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