MOLECULAR DYNAMICS SIMULATIONS OF GRANULAR MATERIALS

When sand or other granular materials are shaken, poured or sheared many intriguing phenomena can be observed. We will model the granular medium by a packing of elastic spheres and simulate it via Molecular Dynamics. Dissipation of energy and shear friction at collisions are included. The onset of fluidization can be determined and is in good agreement with experiments. On a vibrating plate we observe the formation of convection cells due to walls or amplitude modulations. Density and velocity profiles on conveyor belts are measured and the influence of an obstacle discussed. We mention various types of rheology for flow down an inclined chute or through a pipe and outflowing containers.

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Size-Dependent Elasticity of Silicon Nanowires

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.60-61.315 ◽

2009 ◽

Vol 60-61 ◽

pp. 315-319 ◽

Cited By ~ 3

Author(s):

W.W. Zhang ◽

Qing An Huang ◽

H. Yu ◽

L.B. Lu

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulations ◽

Silicon Nanowires ◽

First Principles ◽

Si Nanowires ◽

Size Dependent ◽

Reconstructed Surfaces ◽

Strain Relationship ◽

Dynamics Simulations ◽

Good Agreement

Molecular dynamics simulations are carried out to characterize the mechanical properties of [001] and [110] oriented silicon nanowires, with the thickness ranging from 1.05nm to 3.24 nm. The nanowires are taken to have ideal surfaces and (2×1) reconstructed surfaces, respectively. A series of simulations for square cross-section Si nanowires have been performed and Young’s modulus is calculated from energy–strain relationship. The results show that the elasticity of Si nanowires is strongly depended on size and surface reconstruction. Furthermore, the physical origin of above results is analyzed, consistent with the bond loss and saturation concept. The results obtained from the molecular dynamics simulations are in good agreement with the values of first-principles. The molecular dynamics simulations combine the accuracy and efficiency.

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Thermal Conductivity of Amorphous and Crystalline SiO2 Nano-Films from Molecular Dynamics Simulations

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.501.64 ◽

2012 ◽

Vol 501 ◽

pp. 64-69 ◽

Cited By ~ 1

Author(s):

Yan He ◽

Yuan Zheng Tang ◽

Man Ding ◽

Lian Xiang Ma

Keyword(s):

Thermal Conductivity ◽

Molecular Dynamics ◽

Film Thickness ◽

Molecular Dynamics Simulations ◽

Grain Morphology ◽

Nonequilibrium Molecular Dynamics ◽

Calculated Temperature ◽

Dynamics Simulations ◽

Different Thickness ◽

Good Agreement

Normal thermal conductivity of amorphous and crystalline SiO2nano-films is calculated by nonequilibrium molecular dynamics (NEMD) simulations in the temperature range from 100 to 700K and thicknesses from 2 to 6nm. The calculated temperature and thickness dependences of thermal conductivity are in good agreement with previous literatures. In the same thickness, higher thermal conductivity is obtained for crystalline SiO2nano-films. And more importantly, for amorphous SiO2nano-films, thickness can be any direction of x, y, z-axis without effect on the normal thermal conductivity, for crystalline SiO2nano-films, the different thickness directions obtain different thermal conductivity results. The different results of amorphous and crystalline SiO2nano-films simply show that film thickness and grain morphology will cause different effects on thermal conductivity.

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Neural network potential for Zr-Rh system by machine learning

Journal of Physics Condensed Matter ◽

10.1088/1361-648x/ac37dc ◽

2021 ◽

Author(s):

Kun Xie ◽

Chong Qiao ◽

Hong Shen ◽

Riyi Yang ◽

Ming Xu ◽

...

Keyword(s):

Neural Network ◽

Machine Learning ◽

Mechanical Property ◽

Molecular Dynamics ◽

Molecular Dynamics Simulations ◽

Structural Features ◽

Ab Initio Molecular Dynamics ◽

The Neural Network ◽

Dynamics Simulations ◽

Good Agreement

Abstract Zr-Rh metallic glass has enabled its many applications in vehicle parts, sports equipment and so on due to its outstanding performance in mechanical property, but the knowledge of the microstructure determining the superb mechanical property remains yet insufficient. Here, we develop a deep neural network potential of Zr-Rh system by using machine learning, which breaks the dilemma between the accuracy and efficiency in molecular dynamics simulations, and greatly improves the simulation scale in both space and time. The results show that the structural features obtained from the neural network method are in good agreement with the cases in ab initio molecular dynamics simulations. Furthermore, we build a large model of 5400 atoms to explore the influences of simulated size and cooling rate on the melt-quenching process of Zr77Rh23. Our study lays a foundation for exploring the complex structures in amorphous Zr77Rh23, which is of great significance for the design and practical application.

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MOLECULAR DYNAMICS SIMULATIONS OF FURAN RESIN (POLYFURFURYL ALCOHOL): PREDICTING MECHANICAL PROPERTIES

10.12783/asc36/35847 ◽

2021 ◽

Author(s):

JOSH KEMPPAINEN ◽

IVAN GALLEGOS ◽

PRATHAMESH DESHPANDE ◽

JACOB GISSINGER ◽

GREGORY ODEGARD

Keyword(s):

Mechanical Properties ◽

Molecular Dynamics ◽

Molecular Dynamics Simulations ◽

Acid Corrosion ◽

Carbon Composites ◽

Corrosion Resistant ◽

Polyfurfuryl Alcohol ◽

Furan Resin ◽

Dynamics Simulations ◽

Good Agreement

Furan resins can be used as precursor resin for Carbon-Carbon Composites but has also been used in adhesives, acid/corrosion resistant materials, and as an alternative fuel precursor [15]. This paper contains the most current understanding of the structure of furan resin and a Molecular Dynamics workflow for computationally simulating its polymerization with the 'fix bond/react' command implemented in LAMMPS. The predicted mechanical properties of the polymerized resin are in good agreement with the literature values.

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Molecular Dynamics Simulations of Granular Materials

The Physics of Granular Media ◽

10.1002/352760362x.ch13 ◽

2004 ◽

pp. 297-324 ◽

Cited By ~ 18

Author(s):

Stefan Luding

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulations ◽

Granular Materials ◽

Dynamics Simulations

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Molecular dynamics simulations of n-butane and n-hexane diffusion in silicalite

Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences ◽

10.1098/rspa.1995.0010 ◽

1995 ◽

Vol 448 (1932) ◽

pp. 143-160 ◽

Cited By ~ 35

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulations ◽

Guest Molecule ◽

Measured Data ◽

Zeolite Framework ◽

Adsorbed Molecules ◽

Molecule Interactions ◽

Dynamics Simulations ◽

And Diffusion ◽

Good Agreement

We report molecular dynamics simulations of n-butane and n-hexane adsorbed in the zeolite silicalite. These systems have been modelled within a rigid framework approximation and a Ryckaert-Bellemans model was adopted to describe the adsorbed molecules. The parametrization due to June, Bell and Theodorou has been used to describe the host-guest molecule interactions. Long simulations (1000 ps) have been performed, modelling these systems at a variety of sorbate loadings and temperatures. These have allowed us to investigate how the presence of the zeolite framework affects the thermodynamic properties, confomational distributions and diffusion related properties of the adsorbed molecules, and their response to changes in the loading and temperature. We have obtained estimates of the diffusion coefficients and activation energies which are in good agreement with experimentally measured data.

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On the Linear Temperature Dependence of Phonon Thermal Boundary Conductance in the Classical Limit

Journal of Heat Transfer ◽

10.1115/1.4003575 ◽

2011 ◽

Vol 133 (7) ◽

Cited By ~ 22

Author(s):

John C. Duda ◽

Pamela M. Norris ◽

Patrick E. Hopkins

Keyword(s):

Molecular Dynamics ◽

Temperature Dependence ◽

Molecular Dynamics Simulations ◽

Classical Limit ◽

Phonon Transport ◽

Linear Temperature Dependence ◽

Linear Temperature ◽

Thermal Boundary Conductance ◽

Dynamics Simulations ◽

Good Agreement

We present a new model for predicting thermal boundary conductance in the classical limit. This model takes a different form than those of the traditionally used mismatch theories in the fact that the temperature dependence of thermal boundary conductance is driven by the phononic scattering mechanisms of the materials comprising the interface as opposed to the heat capacities of those materials. The model developed in this work assumes that a phonon on one side of an interface may not scatter at the interface itself but instead scatter with phonons in the adjacent material via the scattering processes intrinsic in the adjacent material. We find that this model is in good agreement with classical molecular dynamics simulations of phonon transport across a Si/Ge interface.

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Dynamic Fracture Mechanisms in Nanostructured and Amorphous Silica Glasses Million-Atom Molecular Dynamics Simulations

MRS Proceedings ◽

10.1557/proc-703-v3.9 ◽

2001 ◽

Vol 703 ◽

Cited By ~ 7

Author(s):

Laurent Van Brutzel ◽

Cindy L. Rountree ◽

Rajiv K. Kalia ◽

Aiichiro Nakano ◽

Priya Vashishta

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulations ◽

Dynamic Fracture ◽

Crack Front ◽

Fracture Mechanisms ◽

Silica Glasses ◽

Parallel Molecular Dynamics ◽

Dynamics Simulations ◽

Nanostructured Silica ◽

Good Agreement

ABSTRACTParallel molecular dynamics simulations are performed to investigate dynamic fracture in bulk and nanostructured silica glasses at room temperature and 1000 K. In bulk silica the crack front develops multiple branches and nanoscale pores open up ahead of the crack tip. Pores coalesce and then they merge with the advancing crack-front to cause cleavage fracture. The calculated fracture toughness is in good agreement with experiments. In nanostrucutred silica the crack-front meanders along intercluster boundaries, merging with nanoscale pores in these regions to cause intergranular fracture. The failure strain in nanostructured silica is significantly larger than in the bulk systems.

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MOLECULAR DYNAMICS SIMULATIONS OF GRANULAR MATERIALS ON THE INTEL iPSC/860

International Journal of Modern Physics C ◽

10.1142/s0129183192000889 ◽

1992 ◽

Vol 03 (06) ◽

pp. 1281-1293 ◽

Cited By ~ 19

Author(s):

GERALD H. RISTOW

Keyword(s):

Molecular Dynamics ◽

Load Balancing ◽

Molecular Dynamics Simulations ◽

Granular Materials ◽

Distributed Memory ◽

Two Dimensions ◽

Three Dimensions ◽

Parallel Computer ◽

Dynamics Simulations ◽

Specific Implementation

In this paper we present an efficient algorithm to perform Molecular Dynamics simulations on a distributed memory parallel computer, the Intel iPSC/860. The proposed model describes the flow properties of granular materials in two dimensions. The specific implementation on a 32 node iPSC/860, especially the message passing and load balancing algorithms, are discussed in detail. Performance data are shown for different computers and varying node numbers of the iPSC/860. As a physical example we calculate some properties of the outflow behavior from a two-dimensional hopper and we discuss possible extensions of our model to three dimensions. Our simulations show that Molecular Dynamics simulations can be implemented quite efficiently on a distributed memory parallel computer if one assures load balancing and optimizes the internode communications.

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