Annealing study of amorphous bulk and nanoparticle iron using molecular dynamics simulation

2014 ◽  
Vol 28 (23) ◽  
pp. 1450155 ◽  
Author(s):  
P. H. Kien ◽  
M. T. Lan ◽  
N. T. Dung ◽  
P. K. Hung
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy ◽  
Md Simulations ◽  
Amorphous Structure ◽  
Dynamics Simulation ◽  
Structural Defects ◽  
Crystal Lattices ◽  
Annealing Study ◽  
Amorphous States ◽  
Short Time

Annealing study of amorphous bulk and nanoparticle iron at temperatures from 500 K to 1000 K has been carried out using molecular dynamics (MD) simulations. The simulation is performed for models containing 104 particles Fe at both crystalline and amorphous states. We determine changes of the potential energy, pair radial distribution function (PRDF) and distribution of coordination number (DCN) as a function of annealing time. The calculation shows that the aging slightly reduces the potential energy of system. This result evidences that the amorphous sample undergoes different quasi-equilibrated states during annealing. Similar trend is observed for nanoparticles sample. When the samples are annealed at high temperatures we observe the crystallization in both bulk and nanoparticle. In particular, the system undergoes three stages. At first stage the relaxation proceeds slowly so that the energy of system slightly decreases and the samples structure remains amorphous. Within second stage a structural transformation occurs which significantly changes PRDF and DCN for the relatively short time. The energy of the system is dropped considerably and the amorphous structure transforms into the crystalline. Finally, the crystalline sample undergoes the slow relaxation which reduces the energy of system and eliminates structural defects in crystal lattices.

scholarly journals Study of Structural and Phase Transition of Nickel Metal

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Pham Huu Kien
Keyword(s):  
Phase Transition ◽  
Molecular Dynamics ◽  
Distribution Function ◽  
Potential Energy ◽  
Md Simulations ◽  
Structural Defects ◽  
Nickel Metal ◽  
Crystal Lattices ◽  
Annealing Study ◽  
Amorphous States

Annealing study of nickel metal in the temperature range 300–1000 K has been carried out using molecular dynamics (MD) simulations. The simulation is done for models containing 104 particles Ni at both crystalline and amorphous states. We obtain the change as a function of annealing time for the potential energy of system, pair radial distribution function (PRDF), and distribution of coordination number (DCN). The calculation shows that the aging slightly reduces the potential energy of system. This result evidences that the amorphous model undergoes different quasiequilibrated states during annealing. The crystalline model undergoes the slow relaxation which reduces the energy of system and eliminates structural defects in crystal lattices.

scholarly journals Molecular Dynamics Simulation Study of Eucommiaulmoides GUM/AG Nanoparticle Composites

2017 ◽  
Vol 26 (4) ◽  
pp. 096369351702600
Author(s):  
Fei-Zhou Li ◽  
Zhen-Lin Lu ◽  
Yuntao Xi ◽  
Xin-sheng Wang ◽  
Ming-qiang Zhu
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Pressure Coefficient ◽  
Amorphous State ◽  
Md Simulations ◽  
Amorphous Structure ◽  
Dynamics Simulation ◽  
Ag Nanoparticle ◽  
Ag Nps ◽  
Eucommia Ulmoides Gum

A study of eucommia ulmoides gum (EUG)/Ag nanoparticle (NP) composites by molecular dynamics (MD) simulations to understand their structure, polarizability, thermodynamic properties, and mechanical properties is proposed. The effects of simulation temperature and Ag NPs size on these parameters were also studied. The results revealed that the composites exhibited an isotropic amorphous structure, and the distribution uniformity of the Ag NPs was enhanced by changing the simulation temperature. Several atoms of the Ag NPs were in an amorphous state, and a polarized layer was observed on the interface between the Ag NPs and the eucommia ulmoide matrix. The interface size increased as the temperature increased and nanoparticles size decreased. The isochoric heat capacity and thermal pressure coefficient of the EUG/Ag-NP composites exhibited significant size effects and improved thermal interferences, which indicated that the presence of the Ag NPs had a positive effect on the mechanical properties of the EUG.

Effect of Initial Indentation Position on Plastic Deformation Behaviors of Polycrystalline Materials via Molecular Dynamics Simulation

NANO ◽  
2019 ◽  
Vol 14 (01) ◽  
pp. 1950001 ◽  
Author(s):  
Pengyue Zhao ◽  
Yongbo Guo
Keyword(s):  
Molecular Dynamics ◽  
Plastic Deformation ◽  
Potential Energy ◽  
Internal Stress ◽  
Position Effect ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Polycrystalline Materials ◽  
Indentation Force ◽  
Deformation Behaviors

Polycrystalline materials can be divided into four types of microstructural components, including grain cell (GC), grain boundary (GB), triple junction (TJ) and vertex points (VP). Nanoindentation at different microstructural components on the polycrystalline materials surface can lead to different plastic deformation behaviors of the polycrystalline materials. Due to experimental limitations, the indentation-induced internal stress and defect evolution process are difficult to investigate directly, especially for the polycrystalline materials with grain size less than 100[Formula: see text]nm. The molecular dynamics (MD) simulations were performed to unravel the initial indentation position effect on the elasticity/plastic deformation mechanism of polycrystalline copper. The results reveal that the initial indentation position governs the indentation force variation and defect distribution range due to the different dimensionalities of the microstructural components. The defect propagation as well as the internal stress transmission in the GC regions tend to transfer to the low-dimensional microstructural components of the interfaces. In addition, the atomic internal stress and potential energy accumulation/release of the microstructural component atoms during the nanoindentation process are also investigated, revealing that the atomic internal stress and potential energy in the VPs vary earliest, followed by the TJs, GBs and GCs.

scholarly journals Cavitation and Negative Pressure: A Flexible Water Model Molecular Dynamics Simulation

2019 ◽  
Vol 8 (2) ◽  
pp. 172 ◽  
Author(s):  
Gang Liu ◽  
Qiang Fu ◽  
Junjun Kang
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bonds ◽  
Potential Energy ◽  
Negative Pressure ◽  
Room Temperature ◽  
Md Simulations ◽  
Bubble Nucleation ◽  
Dynamics Simulation ◽  
Water Model ◽  
Bubble Generation

The critical negative pressure for cavitation in water has been theoretically predicted to be in the range of -100 to -200 MPa at room temperature, whereas values around -30 MPa have been obtained by many experiments. The discrepancy has yet to be resolved. Molecular dynamics (MD) is an effective method of observing bubble nucleation, however, most MD simulations use a rigid water model and do not take the effects of intermolecular vibrations into account. In this manuscript we perform MD simulations to study cavitation in water by using a TIP4P/2005f model under volumecontrolled stretching. It is found that the critical negative pressure of water was -168 MPa in the simulation and the critical negative pressure of water containing 50 oxygen molecules was -150 MPa. Hydrogen bonds played a major role in the cavitation process: the breaking of hydrogen bonds promoted bubble generation and growth. The O-H bond could release energy to increase the amount of potential energy in the system, so that cavitation was more likely to occur. When cavitation occurred, the O-H bond could absorb energy to reduce the amount of potential energy in the system, which will promote the growth of bubbles, and stabilise the cavitation bubbles.

Nonadiabatic molecular dynamics simulation for the ultrafast photoisomerization of dMe-OMe-NAIP based on TDDFT on-the-fly potential energy surfaces

2021 ◽  
Vol 23 (9) ◽  
pp. 5236-5243
Author(s):  
Ying Hu ◽  
Chao Xu ◽  
Linfeng Ye ◽  
Feng Long Gu ◽  
Chaoyuan Zhu
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Dynamics Simulation ◽  
Surface Hopping ◽  
Nonadiabatic Molecular Dynamics ◽  
Energy Surfaces

Global switching on-the-fly trajectory surface hopping molecular dynamics simulation was performed on the accurate TD-B3LYP/6-31G* potential energy surfaces for E-to-Z and Z-to-E photoisomerization of dMe-OMe-NAIP up to S1(ππ*) excitation.

scholarly journals Understanding Covalent Grafting of Nanotubes onto Polymer Nanocomposites: Molecular Dynamics Simulation Study

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2621
Author(s):  
Seunghwa Yang
Keyword(s):  
Molecular Dynamics ◽  
Load Transfer ◽  
Cell Model ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Covalent Grafting ◽  
Modelling Strategies ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
External Loads

Here, we systematically interrogate the effects of grafting single-walled (SWNT) and multi-walled carbon nanotubes (MWNT) to polymer matrices by using molecular dynamics (MD) simulations. We specifically investigate key material properties that include interfacial load transfer, alteration of nanotube properties, and dispersion of nanotubes in the polymer matrix. Simulations are conducted on a periodic unit cell model of the nanocomposite with a straight carbon nanotube and an amorphous polyethylene terephthalate (PET) matrix. For each type of nanotube, either 0%, 1.55%, or 3.1% of the carbon atoms in the outermost nanotubes are covalently grafted onto the carbon atoms of the PET matrix. Stress-strain curves and the elastic moduli of nanotubes and nanocomposites are determined based on the density of covalent grafting. Covalent grafting promotes two rivalling effects with respect to altering nanotube properties, and improvements in interfacial load transfer in the nanocomposites are clearly observed. The enhanced interface enables external loads applied to the nanocomposites to be efficiently transferred to the grafted nanotubes. Covalent functionalization of the nanotube surface with PET molecules can alter the solubility of nanotubes and improve dispersibility. Finally, we discuss the current limitations and challenges in using molecular modelling strategies to accurately predict properties on the nanotube and polymers systems studied here.

A Study on the Uniaxial Tension of FCC Metals at Nano Level Using MD

2008 ◽  
Vol 32 ◽  
pp. 255-258
Author(s):  
Bohayra Mortazavi ◽  
Akbar Afaghi Khatibi
Keyword(s):  
Molecular Dynamics ◽  
Uniaxial Tension ◽  
Md Simulations ◽  
Dynamics Simulation ◽  
Face Centered Cubic ◽  
Engineering Strain ◽  
Fcc Metals ◽  
Engineering Stress ◽  
Nano Science ◽  
Face Centered

Molecular Dynamics (MD) are now having orthodox means for simulation of matter in nano-scale. It can be regarded as an accurate alternative for experimental work in nano-science. In this paper, Molecular Dynamics simulation of uniaxial tension of some face centered cubic (FCC) metals (namely Au, Ag, Cu and Ni) at nano-level have been carried out. Sutton-Chen potential functions and velocity Verlet formulation of Noise-Hoover dynamic as well as periodic boundary conditions were applied. MD simulations at different loading rates and temperatures were conducted, and it was concluded that by increasing the temperature, maximum engineering stress decreases while engineering strain at failure is increasing. On the other hand, by increasing the loading rate both maximum engineering stress and strain at failure are increasing.

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 An Analysis Based on Molecular Docking and Molecular Dynamics Simulation Study of Bromelain as Anti-SARS-CoV-2 Variants

2021 ◽  
Vol 12 ◽  
Author(s):  
Trina Ekawati Tallei ◽  
Fatimawali ◽  
Afriza Yelnetty ◽  
Rinaldi Idroes ◽  
Diah Kusumawaty ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Docking ◽  
Molecular Dynamics Simulation ◽  
Three Dimensional ◽  
Md Simulations ◽  
Inhibitory Effect ◽  
Dynamics Simulation ◽  
Novel Coronavirus

The rapid spread of a novel coronavirus known as SARS-CoV-2 has compelled the entire world to seek ways to weaken this virus, prevent its spread and also eliminate it. However, no drug has been approved to treat COVID-19. Furthermore, the receptor-binding domain (RBD) on this viral spike protein, as well as several other important parts of this virus, have recently undergone mutations, resulting in new virus variants. While no treatment is currently available, a naturally derived molecule with known antiviral properties could be used as a potential treatment. Bromelain is an enzyme found in the fruit and stem of pineapples. This substance has been shown to have a broad antiviral activity. In this article, we analyse the ability of bromelain to counteract various variants of the SARS-CoV-2 by targeting bromelain binding on the side of this viral interaction with human angiotensin-converting enzyme 2 (hACE2) using molecular docking and molecular dynamics simulation approaches. We have succeeded in making three-dimensional configurations of various RBD variants using protein modelling. Bromelain exhibited good binding affinity toward various variants of RBDs and binds right at the binding site between RBDs and hACE2. This result is also presented in the modelling between Bromelain, RBD, and hACE2. The molecular dynamics (MD) simulations study revealed significant stability of the bromelain and RBD proteins separately up to 100 ns with an RMSD value of 2 Å. Furthermore, despite increases in RMSD and changes in Rog values of complexes, which are likely due to some destabilized interactions between bromelain and RBD proteins, two proteins in each complex remained bonded, and the site where the two proteins bind remained unchanged. This finding indicated that bromelain could have an inhibitory effect on different SARS-CoV-2 variants, paving the way for a new SARS-CoV-2 inhibitor drug. However, more in vitro and in vivo research on this potential mechanism of action is required.

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