Fracture in Silicon Nitride and Alumina thin Films: a Molecular Dynamics Study

1996 ◽  
Vol 446 ◽  
Author(s):  
Timothy J. Campbell ◽  
Aiichiro Nakano ◽  
Andrey Omeltchenko ◽  
Rajiv K. Kalia ◽  
Priya Vashishta
Keyword(s):  
Thin Films ◽  
Molecular Dynamics ◽  
Silicon Nitride ◽  
Large Scale ◽  
Md Simulations ◽  
Parallel Computers ◽  
Dynamic Correlations ◽  
Fracture Dynamics ◽  
Dynamic Charge ◽  
Effects Of Temperature

AbstractFracture in thin films of silicon nitride and alumina is investigated with large-scale multiresolution molecular-dynamics (MD) simulations on parallel computers. The simulations for alumina include dynamic charge transfer effects based on electronegativity equalization. Results for structural and dynamic correlations and the effects of temperature and orientation of film on fracture dynamics and morphology of fracture surfaces are presented.

Early Stages of Sintering of Si3N4 Nanoclusters Via Parallel Molecular Dynamics

1995 ◽  
Vol 408 ◽  
Author(s):  
Kenji Tsuruta ◽  
Andrey Omeltchenko ◽  
Rajiv K. Kalia ◽  
Priya Vashishta
Keyword(s):  
Molecular Dynamics ◽  
Silicon Nitride ◽  
Neck Region ◽  
Md Simulations ◽  
Parallel Computers ◽  
Early Stages ◽  
Parallel Molecular Dynamics ◽  
Rapid Diffusion ◽  
A Chain

AbstractWe investigate early stages of sintering of silicon nitride (Si3N4) nanoclusters by molecular-dynamics (MD) simulations on parallel computers. Within 100 pico seconds, an asymmetric neck is formed between nanocrystals at 2,000K. In the neck region, there are more four-fold than three-fold coordinated Si atoms. In contrast, amorphous nanoclusters develop a symmetric neck, which has nearly the same number of three-fold and four-fold coordinated Si atoms. In the case of sintering among three nanoclusters, a chain-like structure forms in 200 pico seconds. The present study shows that sintering is driven by rapid diffusion of surface atoms and cluster rearrangement.

Fracture of Nanophase Ceramics: A Molecular-Dynamics Study

1996 ◽  
Vol 457 ◽  
Author(s):  
Aiichiro Nakano ◽  
Rajiv K. Kalia ◽  
Andrey Omeltchenko ◽  
Kenji Tsuruta ◽  
Priya Vashishta
Keyword(s):  
Molecular Dynamics ◽  
Silicon Nitride ◽  
Load Balancing ◽  
Molecular Dynamics Simulations ◽  
Dynamic Fracture ◽  
Parallel Computers ◽  
Fracture Surfaces ◽  
Affine Structures ◽  
Dynamics Simulations ◽  
Multiscale Algorithms

ABSTRACTNew multiscale algorithms and a load-balancing scheme are combined for molecular-dynamics simulations of nanocluster-assembled ceramics on parallel computers. Million-atom simulations of the dynamic fracture in nanophase silicon nitride reveal anisotropie self-affine structures and crossover phenomena associated with fracture surfaces.

Molecular Dynamics Simulation of a Pullout Test on a Carbon Nanotube in a Polymer Matrix

2014 ◽  
Vol 1700 ◽  
pp. 61-66
Author(s):  
Guttormur Arnar Ingvason ◽  
Virginie Rollin
Keyword(s):  
Molecular Dynamics ◽  
Polymer Matrix ◽  
Large Scale ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Atomistic Simulations ◽  
Polymer Molecules ◽  
Molecular Potential ◽  
Pull Out ◽  
Walled Carbon Nanotubes

ABSTRACTAdding single walled carbon nanotubes (SWCNT) to a polymer matrix can improve the delamination properties of the composite. Due to the complexity of polymer molecules and the curing process, few 3-D Molecular Dynamics (MD) simulations of a polymer-SWCNT composite have been run. Our model runs on the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), with a COMPASS (Condensed phase Optimized Molecular Potential for Atomistic Simulations Studies) potential. This potential includes non-bonded interactions, as well as bonds, angles and dihedrals to create a MD model for a SWCNT and EPON 862/DETDA (Diethyltoluenediamine) polymer matrix. Two simulations were performed in order to test the implementation of the COMPASS parameters. The first one was a tensile test on a SWCNT, leading to a Young’s modulus of 1.4 TPa at 300K. The second one was a pull-out test of a SWCNT from an originally uncured EPON 862/DETDA matrix.

scholarly journals Antimicrobial action of the cationic peptide, chrysophsin-3: a coarse-grained molecular dynamics study

Soft Matter ◽  
2018 ◽  
Vol 14 (15) ◽  
pp. 2796-2807 ◽  
Author(s):  
Andrea Catte ◽  
Mark R. Wilson ◽  
Martin Walker ◽  
Vasily S. Oganesyan
Keyword(s):  
Molecular Dynamics ◽  
Large Scale ◽  
Md Simulations ◽  
Antimicrobial Action ◽  
Coarse Grained ◽  
Cationic Peptide ◽  
Coarse Grained Molecular Dynamics

Antimicrobial action of a cationic peptide is modelled by large scale MD simulations.

scholarly journals Molecular dynamics simulations for genetic interpretation in protein coding regions: where we are, where to go and when

2019 ◽  
Author(s):  
Juan J Galano-Frutos ◽  
Helena García-Cebollada ◽  
Javier Sancho
Keyword(s):  
Molecular Dynamics ◽  
Amino Acid ◽  
Large Scale ◽  
Binary Classification ◽  
Chemical Properties ◽  
Md Simulations ◽  
Single Amino Acid ◽  
Medical Decision ◽  
Evolutionary Information ◽  
Protein Variants

Abstract The increasing ease with which massive genetic information can be obtained from patients or healthy individuals has stimulated the development of interpretive bioinformatics tools as aids in clinical practice. Most such tools analyze evolutionary information and simple physical–chemical properties to predict whether replacement of one amino acid residue with another will be tolerated or cause disease. Those approaches achieve up to 80–85% accuracy as binary classifiers (neutral/pathogenic). As such accuracy is insufficient for medical decision to be based on, and it does not appear to be increasing, more precise methods, such as full-atom molecular dynamics (MD) simulations in explicit solvent, are also discussed. Then, to describe the goal of interpreting human genetic variations at large scale through MD simulations, we restrictively refer to all possible protein variants carrying single-amino-acid substitutions arising from single-nucleotide variations as the human variome. We calculate its size and develop a simple model that allows calculating the simulation time needed to have a 0.99 probability of observing unfolding events of any unstable variant. The knowledge of that time enables performing a binary classification of the variants (stable-potentially neutral/unstable-pathogenic). Our model indicates that the human variome cannot be simulated with present computing capabilities. However, if they continue to increase as per Moore’s law, it could be simulated (at 65°C) spending only 3 years in the task if we started in 2031. The simulation of individual protein variomes is achievable in short times starting at present. International coordination seems appropriate to embark upon massive MD simulations of protein variants.

scholarly journals Hydrogenation Dynamics of Biphenylene Carbon (Graphenylene) Membranes

MRS Advances ◽  
2017 ◽  
Vol 2 (29) ◽  
pp. 1571-1576
Author(s):  
Vinicius Splugues ◽  
Pedro Alves da Silva Autreto ◽  
Douglas S. Galvao
Keyword(s):  
Molecular Dynamics ◽  
Large Scale ◽  
Materials Science ◽  
Md Simulations ◽  
Structural Transformations ◽  
Extensive Study ◽  
Massively Parallel ◽  
Porous Membranes ◽  
Two Dimensional ◽  
Reactive Force

ABSTRACTThe advent of graphene created a revolution in materials science. Because of this there is a renewed interest in other carbon-based structures. Graphene is the ultimate (just one atom thick) membrane. It has been proposed that graphene can work as impermeable membrane to standard gases, such argon and helium. Graphene-like porous membranes, but presenting larger porosity and potential selectivity would have many technological applications. Biphenylene carbon (BPC), sometimes called graphenylene, is one of these structures. BPC is a porous two-dimensional (planar) allotrope carbon, with its pores resembling typical sieve cavities and/or some kind of zeolites. In this work, we have investigated the hydrogenation dynamics of BPC membranes under different conditions (hydrogenation plasma density, temperature, etc.). We have carried out an extensive study through fully atomistic molecular dynamics (MD) simulations using the reactive force field ReaxFF, as implemented in the well-known Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code. Our results show that the BPC hydrogenation processes exhibit very complex patterns and the formation of correlated domains (hydrogenated islands) observed in the case of graphene hydrogenation was also observed here. MD results also show that under hydrogenation BPC structure undergoes a change in its topology, the pores undergoing structural transformations and extensive hydrogenation can produce significant structural damages, with the formation of large defective areas and large structural holes, leading to structural collapse.

scholarly journals Indentation-induced plastic behaviour of nanotwinned Cu/high entropy alloy FeCoCrNi nanolaminate: an atomic simulation

RSC Advances ◽  
2020 ◽  
Vol 10 (16) ◽  
pp. 9187-9192 ◽  
Author(s):  
Hui Feng ◽  
Jingwen Tang ◽  
Haotian Chen ◽  
Yuanyuan Tian ◽  
Qihong Fang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Large Scale ◽  
Md Simulations ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Atomic Simulation ◽  
Layer Number ◽  
Plastic Behaviour

Using large-scale molecular dynamics (MD) simulations, the effects of interface and layer number in the nanoindentation response of experimentally observed nanotwinned Cu/high entropy alloy (HEA) FeCoCrNi nanolaminate are studied.

IMD: A Software Package for Molecular Dynamics Studies on Parallel Computers

1997 ◽  
Vol 08 (05) ◽  
pp. 1131-1140 ◽  
Author(s):  
J. Stadler ◽  
R. Mikulla ◽  
H.-R. Trebin
Keyword(s):  
Molecular Dynamics ◽  
Software Package ◽  
Large Scale ◽  
Md Simulation ◽  
Parallel Computers ◽  
Massively Parallel ◽  
Massively Parallel Computers ◽  
Communication Scheme ◽  
And Performance ◽  
Dynamics Simulations

We report on implementation and performance of the program IMD, designed for short range molecular dynamics simulations on massively parallel computers. After a short explanation of the cell-based algorithm, its extension to parallel computers as well as two variants of the communication scheme are discussed. We provide performance numbers for simulations of different sizes and compare them with values found in the literature. Finally we describe two applications, namely a very large scale simulation with more than 1.23×109 atoms, to our knowledge the largest published MD simulation up to this day and a simulation of a crack propagating in a two-dimensional quasicrystal.

scholarly journals A Virtual Reality Ensemble Molecular Dynamics Workflow to Study Complex Conformational Changes in Proteins

2020 ◽  
Author(s):  
Jordi Juárez-Jiménez ◽  
Philip Tew ◽  
Michael o'connor ◽  
Salome Llabres ◽  
Rebecca Sage ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Virtual Reality ◽  
Conformational Changes ◽  
Large Scale ◽  
A Priori ◽  
Computational Cost ◽  
Md Simulations ◽  
Collective Variables ◽  
Sampling Protocols ◽  
State Models

<p>Molecular dynamics (MD) simulations are increasingly used to elucidate relationships between protein structure, dynamics and their biological function. Currently it is extremely challenging to perform MD simulations of large-scale structural rearrangements in proteins that occur on millisecond timescales or beyond, as this requires very significant computational resources, or the use of cumbersome ‘collective variable’ enhanced sampling protocols. Here we describe a framework that combines ensemble MD simulations and virtual-reality visualization (eMD-VR) to enable users to interactively generate realistic descriptions of large amplitude, millisecond timescale protein conformational changes in proteins. Detailed tests demonstrate that eMD-VR substantially decreases the computational cost of folding simulations of a WW domain, without the need to define collective variables <i>a priori</i>. We further show that eMD-VR generated pathways can be combined with Markov State Models to describe the thermodynamics and kinetics of large-scale loop motions in the enzyme cyclophilin A. Our results suggest eMD-VR is a powerful tool for exploring protein energy landscapes in bioengineering efforts. </p>

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