PHASE CHANGES IN ICOSAHEDRAL 54-, 55-, 56-ATOM PLATINUM CLUSTERS

2004 ◽  
Vol 15 (07) ◽  
pp. 981-988 ◽  
Author(s):  
ALI SEBETCI ◽  
ZIYA B. GÜVENÇ ◽  
HATICE KÖKTEN
Keyword(s):  
Global Minimum ◽  
Melting Process ◽  
Melting Behavior ◽  
Phase Changes ◽  
Dynamics Simulation ◽  
Analysis Method ◽  
Embedded Atom ◽  
Platinum Clusters ◽  
Specific Temperature ◽  
Physical Quantities

Using the Voter and Chen version of an embedded-atom model, derived by fitting simultaneously to experimental data both the diatomic molecule and bulk platinum, we have studied the melting behavior of free, icosahedral, 54-, 55- and 56-atom platinum clusters in the molecular dynamics simulation technique. We present an atom-resolved analysis method that includes physical quantities such as the root-mean-square bond-length fluctuation and coordination number for individual atoms as functions of temperature. The effect of a central atom in the icosahedral structure to the melting process is discussed. The results show that the global minimum structures of the 54-, 55- and 56-atom Pt clusters do not melt at a specific temperature, rather, melting processes take place over a finite temperature range. The heat capacity peaks are not δ-functions, but instead remain finite. An ensemble of clusters in the melting region is a mixture of solid-like and liquid-like clusters.

Ab-Inito Data for Interatomic Interactions in Zr-Rich ZrCu Alloys and Embedded-Atom-Method Potentials

2007 ◽  
Vol 561-565 ◽  
pp. 1259-1262 ◽  
Author(s):  
M. Asato ◽  
R. Tamura ◽  
N. Fujima ◽  
T. Hoshino
Keyword(s):  
Ab Initio ◽  
Dynamics Simulation ◽  
Embedded Atom Method ◽  
Atomic Structures ◽  
Embedded Atom ◽  
Atomic Interactions ◽  
The Stability ◽  
Ab Inito ◽  
Physical Quantities ◽  
Reliable Interaction

The quantitative study for the stability of local atomic structures in bulk metallic glasses (BMGs) with temperature effect on physical quantities of BMGs needs the molecular dynamics simulation with the reliable interaction parameter model such as the Embedded-atom-method potentials (EAMPs) which reproduce the ab-initio data as well as the experimental data. We present the ab-initio data for inter-atomic interactions of Zr-rich ZrCu alloys and a preliminary result for the EAMPs of Zr-rich ZrCu alloys.

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.

MOLECULAR DYNAMICS SIMULATION STUDY OF ATOMIC SEGREGATION OF (PdPt)147 DURING THE HEATING PROCESS

2012 ◽  
Vol 26 (08) ◽  
pp. 1250051 ◽  
Author(s):  
X. Y. XIAO ◽  
Z. F. CHENG ◽  
J. H. XIA
Keyword(s):  
Molecular Dynamics ◽  
Melting Process ◽  
Dynamics Simulation ◽  
Heating Process ◽  
Embedded Atom Method ◽  
Bimetallic Cluster ◽  
Embedded Atom ◽  
Atomic Segregation ◽  
Segregation Process ◽  
Alloy Concentration

Research on the influence of alloy concentration and distribution on bimetallic cluster plays a key role in exploring new structural material. This paper studies the melting process of icosahedral bimetallic cluster (PdPt)147 with different Pt concentrations and different atomic distributions by using molecular dynamics with an embedded atom method. The results indicate that the mixed Pd–Pt cluster shows an irregular phenomenon between 580 and 630 K, i.e. the atomic energy decreases with the increase of temperature. This is because the surface energy of Pd is lower than that of Pt; the decreased energy due to Pd atomic segregation is larger than the increased energy due to heating during the segregation process. In addition, the temperature of Pd atomic segregation is strongly related to Pt concentration. This leads to that Pd atoms prefer to remain on the surface even after the cluster melted.

STRUCTURE AND DYNAMICAL PROPERTIES OF AuN, N = 12–14 CLUSTERS: MOLECULAR DYNAMICS SIMULATION

2005 ◽  
Vol 16 (01) ◽  
pp. 99-116 ◽  
Author(s):  
ERDEM K. YILDIRIM ◽  
MURAT ATİŞ ◽  
ZİYA B. GÜVENÇ
Keyword(s):  
Molecular Dynamics ◽  
Thermal Quenching ◽  
Melting Behavior ◽  
Dynamics Simulation ◽  
Embedded Atom Method ◽  
Coordination Numbers ◽  
Embedded Atom ◽  
Long Time ◽  
Time Average ◽  
Short Time

Using molecular dynamics and thermal quenching methods on the basis of Voter–Chen version of the embedded-atom method, we have studied the melting behavior of Au N (N = 12, 13, 14) clusters. This behavior is described in terms of overall and atom resolved root-mean-square bond-length fluctuations, specific-heat, short- and long-time average coordination numbers of each atom and short-time average temperatures of the clusters. The isomer sampling probabilities are obtained from the thermal quenching of the molten clusters, and their energy-spectrum widths are investigated. Phase change of a cluster takes place with the collective and simultaneous motion of all the atoms.

scholarly journals Molecular Dynamics Simulation of the Coalescence and Melting Process of Cu and Ag Nanoparticles

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Hui Guo ◽  
LinFu Zhang ◽  
Qiang Zhu ◽  
ChuanJie Wang ◽  
Gang Chen ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Twin Boundary ◽  
Ag Nanoparticles ◽  
Melting Process ◽  
Melting Behavior ◽  
Stacking Fault ◽  
Dynamics Simulation ◽  
Atomic Diffusion ◽  
Heating Process ◽  
Joint Interface

The coalescence and melting process of different sizes and arrangements of Ag and Cu nanoparticles is studied through the molecular dynamics (MD) method. The results show that the twin boundary or stacking fault formation and atomic diffusion of the nanoparticles play an important role in the different stages of the heating process. At the beginning of the simulation, Cu and Ag nanoparticles will contact to each other in a very short time. As the temperature goes up, Cu and Ag nanoparticles may generate stacking fault or twin boundary to stabilize the interface structure. When the temperature reaches a critical value, the atoms gain a strong ability to diffuse and eventually melt into one liquid sphere. The coalescence point and melting temperature increase as cluster diameter increases. Moreover, the arrangement of Cu and Ag nanoparticles has a certain effect on the stability of the initial joint interface, which will affect subsequent coalescence and melting behavior.

Simulation of Stress Distribution and Mechanical Response of Metallic Glasses

1998 ◽  
Vol 554 ◽  
Author(s):  
Y. Kogure ◽  
M. Doyama
Keyword(s):  
Stress Distribution ◽  
Metallic Glasses ◽  
Mechanical Response ◽  
Local Density ◽  
Glassy State ◽  
Dynamics Simulation ◽  
Single Atom ◽  
Atomic Interaction ◽  
Embedded Atom ◽  
Embedded Atom Method Potential

AbstractMolecular dynamics simulation of the metallic glasses has been done. The embedded atom method potential function for copper is used to express the atomic interaction. The stress distribution in the glassy state is evaluated from specific volume occupied by single atom and local density in divided cells. The displacements of individual atom under the shear stress are calculated and the correlation between the displacements and the atomic volumes are investigated.

Reaction Heat of High Alkali Aluminosilicate Glass Batches in Melting Process

2014 ◽  
Vol 852 ◽  
pp. 71-75 ◽  
Author(s):  
Ying Liang Tian ◽  
Jin Shu Cheng ◽  
Jing Zhang ◽  
Yan Li Shao ◽  
Xiao Li
Keyword(s):  
Raw Materials ◽  
Melting Process ◽  
Aluminosilicate Glass ◽  
Heating Process ◽  
Analysis Method ◽  
Optimization Scheme ◽  
Reaction Heat ◽  
Significant Difference ◽  
Carbonate Decomposition ◽  
High Alkali

High alkali aluminosilicate glass batches were prepared by five different raw materials, reaction heat of which in melting process was studied by means of DSC thermal analysis method. The results show that reaction heat of batches in the heating process of 25-1600°C exists a significant difference, and which is among 4396.38 J/g-5311.14 J/g, moreover the least is the batches using petalite, while the most is spodumene. In the whole heating process, 380-800°C is carbonate decomposition stage, which accounts for 42-46% of the total absorbed heat; and 800-1200°C is silicate reaction stage, 40-50%; and 1200-1600°C is glass clarify and homogenization phase , 6%-16%. Therefore, carbonate decomposition and silicate reaction is the main part of batches heat consumption, the optimization scheme for materials has a significant effect on energy saving and emission reduction.

Development of homogeneous/heterogeneous reaction in flow based through non-Darcy Forchheimer medium

2017 ◽  
Vol 16 (05) ◽  
pp. 1750045 ◽  
Author(s):  
Tasawar Hayat ◽  
Faisal Shah ◽  
Ahmed Alsaedi ◽  
Muhammad Ijaz Khan
Keyword(s):  
Magnetic Parameter ◽  
Heterogeneous Reaction ◽  
Phase Changes ◽  
Heterogeneous Reactions ◽  
Medium Effect ◽  
Effect Of Temperature ◽  
Temperature Phase ◽  
Surface Thermodynamics ◽  
Isothermal Model ◽  
Physical Quantities

The objective here is to analyze the influence of homogeneous and heterogeneous reactions in flow induced by convectively heated sheet with nonlinear velocity and variable thickness. Porous medium effect is characterized by Darcy–Forchheimer consideration. A simple isothermal model of homogeneous–heterogeneous reactions is used to regulate the temperature of stretched surface. Thermodynamics processes of homogeneous–heterogeneous reactions analyze the effect of temperature phase changes. Resulting problems are computed for the convergent solutions of velocity, temperature and concentration. Analysis for the influential variables on the physical quantities is graphically examined. Our computed results interpret that velocity field decays for larger magnetic parameter while temperature field enhances for higher estimation of Biot number.

Molecular Dynamics Simulation of Sputtering with Mmany-Body Interactions

1988 ◽  
Vol 100 ◽  
Author(s):  
Davy Y. Lo ◽  
Tom A. Tombrello ◽  
Mark H. Shapiro ◽  
Don E. Harrison
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Single Crystal ◽  
Low Energy ◽  
Dynamics Simulation ◽  
Embedded Atom Method ◽  
Many Body ◽  
Embedded Atom ◽  
Dynamics Simulations ◽  
Small Single Crystal

ABSTRACTMany-body forces obtained by the Embedded-Atom Method (EAM) [41 are incorporated into the description of low energy collisions and surface ejection processes in molecular dynamics simulations of sputtering from metal targets. Bombardments of small, single crystal Cu targets (400–500 atoms) in three different orientations ({100}, {110}, {111}) by 5 keV Ar+ ions have been simulated. The results are compared to simulations using purely pair-wise additive interactions. Significant differences in the spectra of ejected atoms are found.

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.

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