Million atom molecular dynamics simulations of materials on parallel computers

Vashishta, P.; Kalia, Rajiv K.; Li, Wei; Nakanos, Aiichiro; Omeltchenko, Andrey; Tsuruta, Kenji; Wang, Jinghan; Ebbsjö, Ingvar

doi:10.1016/s1359-0286(96)80113-6

Cited by 10 publications

(9 citation statements)

References 45 publications

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“…Subsequently, the boundary layer atoms are frozen until the strain is further increased. (72,74,75). Initially, the atoms in the sheet are in the x-y plane, but during the course of the simulation they are allowed to move in the z-direction as well.…”

Section: Crack Branching In Graphine and Gaasmentioning

confidence: 99%

Atomistic Aspects of Crack Propagation in Brittle Materials: Multimillion Atom Molecular Dynamics Simulations

Rountree

Kalia

Lidorikis

et al. 2002

Annu. Rev. Mater. Res.

188

115

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Atomistic aspects of dynamic fracture in a variety of brittle crystalline, amorphous, nanophase, and nanocomposite materials are reviewed. Molecular dynamics (MD) simulations, ranging from a million to 1.5 billion atoms, are performed on massively parallel computers using highly efficient multiresolution algorithms. These simulations shed new light on (a) branching, deflection, and arrest of cracks; (b) growth of nanoscale pores ahead of the crack and how pores coalesce with the crack to cause fracture; and (c) the influence of these mechanisms on the morphology of fracture surfaces. Recent advances in novel multiscale simulation schemes combining quantum mechanical, molecular dynamics, and finite-element approaches and the use of these hybrid approaches in the study of crack propagation are also discussed.

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Section: Crack Branching In Graphine and Gaasmentioning

confidence: 99%

Atomistic Aspects of Crack Propagation in Brittle Materials: Multimillion Atom Molecular Dynamics Simulations

Rountree

Kalia

Lidorikis

et al. 2002

Annu. Rev. Mater. Res.

188

115

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“…As such the classical mechanics approximation is usually safely made for metals (as they are typically heavier elements with close separation between particles), at typical engineering temperatures: -40C up to phase change temperatures, although there are numerous studies that have pushed the lower limit threshold even further 4,5 and have been able to successfully model mechanical properties of metals at very low absolute temperatures.…”

Section: Physical Characteristics and Important Physical Quantitiesmentioning

confidence: 99%

Variable time domain discretization methodology for molecular dynamics simulation of metallic compounds

Zeinalov¹

2021

Preprint

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The present work proposes a methodology to improve the computational requirements of molecular dynamics simulations while maintaining or improving the fidelity of the obtained results. The most common method of molecular dynamics simulation at present is the multi-force, constant time-step, explicit computation, which advances a single time step at a time to determine the next state of the system. The present work proposes a variable time-step strategy, where a single large simulation is subdivided into multiple time domains which redistribute computational resources where they are needed the most: in areas of higher than average potential or kinetic energy or highly dynamic areas around impurity clusters, void formations and crack propagations. The research focuses on the simulation of metallic compounds, as these form the basis of most common molecular dynamics simulations, and have been very thoroughly investigated over the years, thus providing a very extensive body of work for the purpose of comparison and validation of the proposed methodology. The novel methodology presented in this work allows to alleviate some of the limitations associated with the molecular dynamics methodologies and go beyond traditional scales of simulation. The proposed method has been observed to deliver 5 to 20 percent increase in simulation size domain while maintaining or improving the accuracy and computational cycle time. The benefits were observed to be greater for large simulations with one or more areas of higher than average kinetic or potential energy levels, such as those found during crack initiation and propagation, coating-substrate interface, localized pressure application or large thermal gradient. The large difference allows for very clear prioritization of computational resources for high energy areas and as a result provides for faster and more accurate simulation even with increased domain size. Conversely, this method has been observed to provide little to no benefit when simulating stable systems that are undergoing very slow change, such as (relatively) slow change in ambient temperature or pressure, or otherwise homogeneous internal and external boundary conditions. However, for the majority of applications described above, including coating deposition and additive manufacturing, the proposed methodology will yield substantial increase in both simulation size and accuracy, since in the aforementioned processes kinetic and potential energy gradients across the simulation are typically very significant

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“…Due to the assumptions we made about the approximate and real structure which states that they have the same crystal structure, the above relation can be simplified for FCC crystal structure as follows: (15) where "N real/Apr " is the number of real unit cells corresponding to an approximate unit cell. In this paper we have approximated a 2 × 2 × 2 crystal structure, which is equivalent to eight unit cells with a 1 × 1 × 1, crystal structure, i.e., single unit cell.…”

Section: Dimensionless-parameter's Name Definitionmentioning

confidence: 99%

“…The spatial size of this number of atoms is still below sub-microns. 14 15 For doing the related calculations, super-computers are needed; but the obtained results are accurate.…”

Section: Introductionmentioning

confidence: 99%

Introducing Structural Approximation Method for Modeling Nanostructures

Momeni¹,

Alasty²

2010

Jnl of Comp & Theo Nano

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In this work a new method for analyzing nanostructured materials has been proposed to accelerate the simulations for solid crystalline materials. The proposed Structural Approximation Method (SAM) is based on Molecular Dynamics (MD) and the accuracy of the results can also be improved in a systematic manner by sacrificing the simulation speed. In this method a virtual material is used instead of the real one, which has less number of atoms and therefore fewer degrees of freedom, compared to the real material. The number of differential equations that must be integrated in order to specify the state of the system will decrease significantly, and the simulation speed increases. To generalize the method for different materials, we used dimensionless equations. A fuzzy estimator is designed to determine the inter-atomic potential of the virtual material such that the virtual material represents the same behavior as the real one. In this paper Gaussian membership functions, singleton fuzzifier, center average defuzzifier, and Mamdani inference engine has been used for designing the fuzzy estimator. We also used the Gear predictor-corrector numerical integration method to integrate the governing differential equations. A FCC nano-bar of copper under uniform axial loading along [1 0 0] has been considered. The Sutton-Chen inter-atomic potential is used. The strain of this nano-bar has been calculated using the MD and the proposed method. Comparing the results show that while the proposed method is much faster, its results remain in an acceptable range from the results of MD method.

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Million atom molecular dynamics simulations of materials on parallel computers

Cited by 10 publications

References 45 publications

Atomistic Aspects of Crack Propagation in Brittle Materials: Multimillion Atom Molecular Dynamics Simulations

Atomistic Aspects of Crack Propagation in Brittle Materials: Multimillion Atom Molecular Dynamics Simulations

Variable time domain discretization methodology for molecular dynamics simulation of metallic compounds

Introducing Structural Approximation Method for Modeling Nanostructures

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