Molecular dynamics simulation of the coalescence and melting process of Au and Cu nano-clusters

2018 ◽  
Vol 32 (06) ◽  
pp. 1850061
Author(s):  
Gang Chen ◽  
Chuan Jie Wang ◽  
Peng Zhang
Keyword(s):  
Shear Deformation ◽  
Melting Process ◽  
Dynamics Simulation ◽  
Particle Rotation ◽  
Interface Diffusion ◽  
Surface And Interface ◽  
Simulation Procedure ◽  
Increasing Temperature ◽  
Deformation Surface ◽  
Cu Nanoclusters

Molecular dynamic (MD) method is used to study the coalescence and fusing process of Au and Cu nanoclusters. The results show that shear deformation, surface and interface diffusion play important role in different stages of all simulation procedure. In most cases, shear deformation produces the twin boundary or/and stacking fault in particles by particle rotation and slide. The angle between the {111} of Au and Cu particles decrease with increasing temperature, which promotes the formation of the stable interface. Furthermore, the coalescence point and melting temperature increase as cluster diameter increases. For the other cases, there are no particle rotation and slide phenomenon in the elevating temperature process because the stable interface can be formed by forming twin boundaries once two particles contact.

scholarly journals Analysis of Pd-Ni Nanobelts Melting Process Using Molecular Dynamics Simulation

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Chen Gang ◽  
Zhang Peng ◽  
Liu HongWei
Keyword(s):  
Md Simulation ◽  
Melting Process ◽  
Pure Metal ◽  
Dynamics Simulation ◽  
Analysis Method ◽  
Melting Points ◽  
Index Pair ◽  
Ni Alloy ◽  
Increasing Temperature ◽  
Pair Analysis

The melting process of Pd-Ni alloy nanobelts with different Ni atom content has been simulated by molecular dynamic (MD) method. The radial distribution function, the Lindemann index, and pair analysis method were used to characterize Pd-Ni nanobelt models in simulation. The results indicate that the melting temperature of Pd-Ni nanobelt with composition far from pure metal was lower than that of other models, and the breaking point of the nanobelt can be illustrated by the Lindemann index. Pair analysis indicates that the number of FCC pairs will decrease and almost disappear at melting point with increasing temperature. The melting points of Pd-Ni alloy nanobelts were also calculated by thermodynamic method, and the results were close to that obtained by MD simulation.

Sputtering of Graphite by Hydrogen Isotopes in the Fusion Environment: A Molecular Dynamics Simulation Study

2018 ◽  
Vol 4 (4) ◽  
Author(s):  
Qiang Zhao ◽  
Yang Li ◽  
Zheng Zhang ◽  
Xiaoping Ouyang
Keyword(s):  
Molecular Dynamics ◽  
Incident Energy ◽  
Large Scale ◽  
Incident Angle ◽  
Hydrogen Isotopes ◽  
Dynamics Simulation ◽  
Calculation Results ◽  
Sputtering Yield ◽  
Increasing Temperature ◽  
Sputtering Yields

The sputtering of graphite due to the bombardment of hydrogen isotopes is crucial to successfully using graphite in the fusion environment. In this work, we use molecular dynamics to simulate the sputtering using the large-scale atomic/molecular massively parallel simulator (lammps). The calculation results show that the peak values of the sputtering yield are between 25 eV and 50 eV. When the incident energy is greater than the energy corresponding to the peak value, a lower carbon sputtering yield is obtained. The temperature that is most likely to sputter is approximately 800 K for hydrogen, deuterium, and tritium. Below the 800 K, the sputtering yields increase with temperature. By contrast, above the 800 K, the yields decrease with increasing temperature. Under the same temperature and incident energy, the sputtering rate of tritium is greater than that of deuterium, which in turn is greater than that of hydrogen. When the incident energy is 25 eV, the sputtering yield at 300 K increases below an incident angle at 30 deg and remains steady after that.

THE EFFECT OF THE RANGE OF THE POTENTIAL ON THE MULTI-STEP CLUSTER MELTING PROCESS

2004 ◽  
Vol 15 (05) ◽  
pp. 649-658 ◽  
Author(s):  
SHI-WEI REN
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Morse Potential ◽  
Melting Process ◽  
Dynamics Simulation ◽  
Repulsive Core ◽  
Tail Region ◽  
Step Process

By using the microcanonical molecular dynamics simulation, the melting processes of the clusters bound by Morse potential are investigated. It is found that these clusters show a multi-step melting process as long as the range of the Morse potential is a suitable value. The origins of this multi-step process are analyzed. I find that not only the repulsive core of the potential but also the attractive tail range of the potential influences the melting process. Moreover, the occurrence of the multi-step melting process is more sensitive to the tail region of the Morse potential.

scholarly journals Effects of the Temperature and the pH on the Main Protease of SARS-CoV-2: A Molecular Dynamics Simulation Study

2021 ◽  
Vol 12 (6) ◽  
pp. 7239-7248
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Root Mean Square ◽  
Dynamics Simulation ◽  
Effect Of Temperature ◽  
Water Molecules ◽  
Mean Square ◽  
Main Protease ◽  
Decreasing Ph ◽  
Increasing Temperature

The novel coronavirus, recognized as COVID-19, is the cause of an infection outbreak in December 2019. The effect of temperature and pH changes on the main protease of SARS-CoV-2 were investigated using all-atom molecular dynamics simulation. The obtained results from the root mean square deviation (RMSD) and root mean square fluctuations (RMSF) analyses showed that at a constant temperature of 25℃ and pH=5, the conformational change of the main protease is more significant than that of pH=6 and 7. Also, by increasing temperature from 25℃ to 55℃ at constant pH=7, a remarkable change in protein structure was observed. The radial probability of water molecules around the main protease was decreased by increasing temperature and decreasing pH. The weakening of the binding energy between the main protease and water molecules due to the increasing temperature and decreasing pH has reduced the number of hydrogen bonds between the main protease and water molecules. Finding conditions that alter the conformation of the main protease could be fundamental because this change could affect the virus’s functionality and its ability to impose illness.

scholarly journals Study of Ni/Al Interface Diffusion by Molecular Dynamics Simulation

Engineering ◽  
2011 ◽  
Vol 03 (03) ◽  
pp. 227-232 ◽  
Author(s):  
Chunguang Zhang ◽  
Hao Wang ◽  
Yishen Qiu
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Dynamics Simulation ◽  
Interface Diffusion

scholarly journals Experimental Study on Wet Skid Resistance of Asphalt Pavements in Icy Conditions

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1201 ◽  
Author(s):  
Yan ◽  
Mao ◽  
Zhong ◽  
Zhang ◽  
Zhang
Keyword(s):  
Surface Friction ◽  
Melting Process ◽  
Asphalt Pavements ◽  
Skid Resistance ◽  
Ice Melting ◽  
Temperature Range ◽  
Bitumen Emulsion ◽  
Image Measure ◽  
The Difference ◽  
Increasing Temperature

In this research, the durability of skid resistance during the ice melting process with temperature increasing from −5 °C to 10 °C was characterized by means of a British Pendulum Skid Tester. Four types of pavement surfaces were prepared and tested. The difference between two antiskid layers prepared with bitumen emulsion was the aggregate. The detailed angularity and form 2D index of fine aggregates used for antiskid surfaces, characterized by means of the Aggregate Image Measure System (AIMS) with micro image analysis methods, were then correlated with British Pendulum Number (BPN) values. Results indicate that skid resistance has the lowest value during the ice-melting process. The investigated antiskid layers can increase the surface friction during icy seasons. In icy conditions, the skid resistance behavior first worsens until reaches the lowest value, and then increases gradually with increasing temperature. Results from ice-melting conditions on four investigated pavement surfaces give the same temperature range where there will be lowest skid resistance. That temperature range is from 3 °C to 5 °C. A thicker ice layer will result in a lower skid resistance property and smaller “lowest BPN”.

scholarly journals Shear-Transformation Zone Activation during Loading and Unloading in Nanoindentation of Metallic Glasses

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1477 ◽  
Author(s):  
Karina E. Avila ◽  
Stefan Küchemann ◽  
Iyad Alabd Alhafez ◽  
Herbert M. Urbassek
Keyword(s):  
Dynamics Simulation ◽  
Minor Effect ◽  
Rate Analysis ◽  
Loading And Unloading ◽  
Shear Transformation ◽  
Shear Transformation Zones ◽  
Experimental Findings ◽  
A Minor ◽  
Increasing Temperature ◽  
Activity Cluster

Using molecular dynamics simulation, we study nanoindentation in large samples of Cu–Zr glass at various temperatures between zero and the glass transition temperature. We find that besides the elastic modulus, the yielding point also strongly (by around 50%) decreases with increasing temperature; this behavior is in qualitative agreement with predictions of the cooperative shear model. Shear-transformation zones (STZs) show up in increasing sizes at low temperatures, leading to shear-band activity. Cluster analysis of the STZs exhibits a power-law behavior in the statistics of STZ sizes. We find strong plastic activity also during the unloading phase; it shows up both in the deactivation of previous plastic zones and the appearance of new zones, leading to the observation of pop-outs. The statistics of STZs occurring during unloading show that they operate in a similar nature as the STZs found during loading. For both cases, loading and unloading, we find the statistics of STZs to be related to directed percolation. Material hardness shows a weak strain-rate dependence, confirming previously reported experimental findings; the number of pop-ins is reduced at slower indentation rate. Analysis of the dependence of our simulation results on the quench rate applied during preparation of the glass shows only a minor effect on the properties of STZs.

Investigation of changes in the arrangement of water molecules and salt ions surrounding different atoms of the DNA molecule during the melting process: a molecular dynamics simulation study

2015 ◽  
Vol 93 (3) ◽  
pp. 348-361 ◽  
Author(s):  
C. Izanloo
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Double Helix ◽  
Melting Process ◽  
Minor Groove ◽  
Dynamics Simulation ◽  
Transition Curve ◽  
Water Molecules ◽  
Major Groove ◽  
Dna Duplex

A molecular dynamics simulation was performed on a B-DNA duplex (CGCGAATTGCGC) at different temperatures. The DNA was immerged in a saltwater medium with 1 mol/L NaCl concentration. The arrangements of water molecules and cations around the different atoms of DNA on the melting pathway were investigated. Almost for all atoms of the DNA by double helix → single-stranded transition, the water molecules released from the DNA duplex and cations were close to single-stranded DNA, but this behavior was not clearly seen at melting temperatures. Therefore, release of water molecules and cations approaching the DNA by the increase of temperature does not have any effect on the sharpness of the transition curve. Most of the water molecules and cations were found to be around the negatively charged phosphate oxygen atoms. The number of water molecules released from the first shell hydration upon melting in the minor groove was higher than in the major groove, and intrusion of cations into the minor groove after melting was higher than into the major groove. The hydrations of imino protons were different from each other and were dependent on DNA bases.

Molecular Dynamics Simulation of Crystallization in an Amorphous Metal during Shear Deformation

2000 ◽  
Vol 39 (Part 2, No. 6B) ◽  
pp. L611-L613 ◽  
Author(s):  
Ryuichi Tarumi ◽  
Akio Ogura ◽  
Masayuki Shimojo ◽  
Kazuki Takashima ◽  
Yakichi Higo
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Shear Deformation ◽  
Amorphous Metal ◽  
Dynamics Simulation
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