scholarly journals Atomic Simulations of U-Mo Under Irradiation: A New Angular Dependent Potential

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1018
Author(s):  
Wenhong Ouyang ◽  
Wensheng Lai ◽  
Jiahao Li ◽  
Jianbo Liu ◽  
Baixin Liu
Keyword(s):  
Irradiation Damage ◽  
Lattice Constants ◽  
Residual Defect ◽  
Atomic Interactions ◽  
Negative Role ◽  
Dependent Potential ◽  
Potential Formalism ◽  
Mo Content ◽  
Dynamics Simulations ◽  
Metallic Nuclear Fuels

Uranium-Molybdenum alloy has been a promising option in the production of metallic nuclear fuels, where the introduction of Molybdenum enhances mechanical properties, corrosion resistance, and dimensional stability of fuel components. Meanwhile, few potential options for molecular dynamics simulations of U and its alloys have been reported due to the difficulty in the description of the directional effects within atomic interactions, mainly induced by itinerant f-electron behaviors. In the present study, a new angular dependent potential formalism proposed by the author’s group has been further applied to the description of the U-Mo systems, which has achieved a moderately well reproduction of macroscopic properties such as lattice constants and elastic constants of reference phases. Moreover, the potential has been further improved to more accurately describe the threshold displacement energy surface at intermediate and short atomic distances. Simulations of primary radiation damage in solid solutions of the U-Mo system have also been carried out and an uplift in the residual defect population has been observed when the Mo content decreases to around 5 wt.%, which corroborates the negative role of local Mo depletion in mitigation of irradiation damage and consequent swelling behavior.

Structural stability of CmTin microclusters and nanoparticles: Molecular–dynamics simulations

2005 ◽  
Vol 1 (4) ◽  
pp. 204-209
Author(s):  
O.B. Malcıoğlu ◽  
Ş. Erkoç
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Binary Systems ◽  
Minimum Energy ◽  
Potential Energy Function ◽  
Md Simulations ◽  
Atomic Interactions ◽  
Dynamics Simulations ◽  
Three Body ◽  
Initial Geometry

The minimum energy structures of CmTin microclusters and nanoparticles have been investigated theoretically by performing molecular–dynamics (MD) simulations. Selected crystalline and completely random initial geometries are considered. The potential energy function (PEF) used in the calculations includes two– and three–body atomic interactions for C-Ti binary systems. Molecular–dynamics simulations have been performed at 1 K and 300 K. It has been found that initial geometry has a very strong influence on relaxed geometry

Solid molecular phases of Hydrogen via constant-pressure first-principles Molecular Dynamics

1997 ◽  
Vol 499 ◽  
Author(s):  
Jorge Kohanoff ◽  
Sandro Scandolo
Keyword(s):  
Molecular Dynamics ◽  
First Principles ◽  
Degrees Of Freedom ◽  
Constant Pressure ◽  
Phase Iii ◽  
Orthorhombic Structure ◽  
Lattice Constants ◽  
Symmetry Phase ◽  
Dynamics Simulations ◽  
Zone Sampling

ABSTRACTBy performing constant pressure ab initio molecular dynamics simulations we analyse the high pressure phases of molecular solid hydrogen. We use a gradient corrected LDA, and a freshly implemented efficient technique for Brillouin zone sampling. An extremely good k-point sampling turns out to be crucial for obtaining the correct ground state. Our constant pressure approach allows us to optimize simultaneously the ori-entational degrees of freedom, the lattice constants, and the space group. This can be done either by a local optimization tehcnique, or by running molecular dynamics (MD) trajectories. The MD allows for the system to undergo structural transformations spontaneously. In the lower pressure, namely for the broken symmetry phase (BSP or phase II), we find a quadrupolar orthorhombic structure, of Pca21 symmetry. By means of an MD investigation, we find, at higher pressures, a slightly distorted orthorhombic structure of Cmc21 symmetry. This structure cannot be straightforwardly identified with the H-A phase (or phase III) because: 1) it is metallic, and 2) the Raman vibron discontinuity would be far too large compared to experiment. In fact, we argue that this phase is the first metallic molecular phase of hydrogen. Metallization would happen then, not via a band-overlap mechanism, but due to a structural transformation. By comparing total enthalpies, we also give suggestions for the structure of phase III.

Study on the Effect of Different Factors of Displacement Cascades in Alpha-Fe by Molecular Dynamics Simulations

2020 ◽  
Author(s):  
Pandong Lin ◽  
Junfeng Nie ◽  
Meidan Liu
Keyword(s):  
Molecular Dynamics ◽  
Tensile Strain ◽  
Vacancy Concentration ◽  
Irradiation Damage ◽  
Effect Of Temperature ◽  
Displacement Cascade ◽  
Rpv Steel ◽  
Dynamics Simulations ◽  
Dynamics Method

Abstract As the key component of RPV steel, α-Fe is under neutron irradiation during its long-term service, and lattice atoms of α-Fe are knocked by neutrons, which leads to irradiation damage. In this paper, molecular dynamics method is conducted to investigate the effect of temperature, vacancy concentration and tensile strain on irradiation-induced damage by displacement cascade simulations in α-Fe. The simulations are performed with primary knock-on atom energies ranging from 0.1 to 5 keV, temperature ranging from 100 to 500K, vacancy concentration ranging from 0% to 1% and applied tensile strain ranging from 0 to 5%. The time evolution of defects produced during displacement cascade can be obtained where the surviving number of Frenkel pairs increases rapidly at first, then decrease and comes to stability finally. The influence of these factors on defect production can be concluded as following: The increase of PKA energy, vacancy concentration and applied tensile strain can lead to the increase of defect numbers. In contrast, the increase of temperature decreases the defect numbers. Vacancies and interstitials cluster size distributions are varied in different case. The results are meaningful to describe some microcosmic mechanisms of RPV steels in nuclear system.

GOLD DEPOSITION ON GaAs(001) SURFACES: MOLECULAR-DYNAMICS SIMULATIONS

2002 ◽  
Vol 13 (06) ◽  
pp. 759-769 ◽  
Author(s):  
ŞAKIR ERKOÇ ◽  
LYNDA AMIROUCHE ◽  
LEILA ROUAIGUIA
Keyword(s):  
Molecular Dynamics ◽  
Gold Atom ◽  
Potential Energy Function ◽  
Gold Deposition ◽  
Many Body ◽  
Atomic Interactions ◽  
Dynamics Simulations ◽  
Three Body ◽  
Body Potential ◽  
Different Characteristics

We have simulated the gold deposition on arsenic and gallium terminated GaAs(001) surfaces at low and room temperatures. It has been found that gallium terminated surface is relatively less stable in comparison to the arsenic terminated surface. On the other hand, a single gold adatom on the surface has different characteristics than full coverage gold atoms on the surface; a single gold atom diffuses into the surface at room temperature. Simulations have been performed by considering classical molecular-dynamics technique using an empirical many-body potential energy function comprising two- and three-body atomic interactions.

Modeling the crystal growth of cubic silicon carbide by molecular dynamics simulations

2002 ◽  
Vol 742 ◽  
Author(s):  
Nicoletta Resta ◽  
Christopher Kohler ◽  
Hans-Rainer Trebin
Keyword(s):  
Molecular Dynamics ◽  
Crystal Growth ◽  
Molecular Dynamics Simulations ◽  
Crystallization Process ◽  
Amorphous Material ◽  
Thick Layer ◽  
Atomic Interactions ◽  
Dynamics Simulations ◽  
Amorphous Sic ◽  
Cubic Silicon Carbide

ABSTRACTThe crystal growth of a seed of cubic SiC into the amorphous material has been investigated by means of classical molecular dynamics simulations. The crystallization process was studied with a set of supercells containing up to 2000 atoms, initially consisting of a 12 Å thick layer of crystalline SiC and a 18 Å thick layer of amorphous SiC at high pressure. The dynamic evolution of crystallization was then followed for several nanoseconds with the simulated annealing technique performed at constant pressure and temperature. The atomic interactions were described by the Tersoff potential. We studied the dependence of the growth process on the crystallographic orientation of the crystalline/amorphous interface by considering three different crystal planes, namely the {100}, {110}, and {111} planes. Within the pressure-temperature range considered in our simulations, we observed the crystal growth only for the {110} and the {111} orientations, but not for the {100} ones. The atomistic details of the growth mechanism are described and discussed.

Structure of a Dissociated Edge Dislocation in Copper

1999 ◽  
Vol 578 ◽  
Author(s):  
L. F. Perondi ◽  
P. Szelestey ◽  
K. Kaski
Keyword(s):  
Molecular Dynamics ◽  
Boundary Conditions ◽  
Edge Dislocation ◽  
Equilibrium Distance ◽  
Embedded Atom ◽  
Equilibrium Size ◽  
Atomic Interactions ◽  
Simulated System ◽  
Dynamics Simulations ◽  
Eam Potential

AbstractThe structure of a dissociated edge dislocation in copper is investigated. Attention is given to the structure of the Shockley partials and the equilibrium size of the fault ribbon. The studies are carried out through Molecular Dynamics simulations. The atomic interactions have been modelled through an Embedded Atom Model (EAM) potential. the implementation of which has been specially designed for this study. Our main results show that the equilibrium distance between partials is very sensitive to the type of boundary conditions imposed on the simulated system.

Molecular dynamics simulations of wafer bonding

2001 ◽  
Vol 681 ◽  
Author(s):  
Kurt Scheerschmidt
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Wafer Bonding ◽  
Tight Binding ◽  
Tight Binding Approximation ◽  
Elementary Processes ◽  
Empirical Potentials ◽  
Atomic Interactions ◽  
Dynamics Simulations ◽  
Interface Structures

ABSTRACTMolecular dynamics simulations using empirical potentials have been employed to describe atomic interactions at interfaces created by the macroscopic wafer bonding process. Investigating perfect or distorted surfaces of different semiconductor materials as well as of silica enables one to study the elementary processes and the resulting defects at the interfaces, and to characterize the ability of the potentials used. Twist rotation due to misalignment and bonding over steps influence strongly the bondability of larger areas. Empirical potentials developed by the bond order tight-binding approximation include ∏-bonds and yield enhanced interface structures, energies, and transferability to new materials systems.

Molecular Dynamics Study of (001) and (111) Thin Fcc Films

1990 ◽  
Vol 187 ◽  
Author(s):  
F.H. Streitz ◽  
K. Sieradzki ◽  
R. C. Cammarata
Keyword(s):  
Molecular Dynamics ◽  
Interatomic Potential ◽  
Analytic Form ◽  
Jones Potential ◽  
Lennard Jones ◽  
Embedded Atom ◽  
Atomic Interactions ◽  
Low Levels ◽  
Dynamics Simulations ◽  
Thermodynamic Instability

AbstractWe report on the results of molecular dynamics simulations of thin unsupported fcc films ranging in thickness from 20 layers to a monolayer. The films were oriented with either (001) or (111) free surface normals. The atomic interactions were modelled using a standard Lennard-Jones potential and a short range analytic form of the embedded atom potential. The elastic moduli of the films were determined by measuring their response to very low levels of applied stress.We find that the embedded atom and Lennard-Jones results are in relative agreement for (001) films and qualitative disagreement for (111) oriented films. We relate these differences to the nature of the interatomic potential and the thermodynamic instability of the (001) surface.

scholarly journals Computational Study on Homogeneous Melting of Benzene Phase I

Crystals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 84 ◽  
Author(s):  
Kenji Mochizuki
Keyword(s):  
Phase I ◽  
Computational Study ◽  
Transient State ◽  
Defect Migration ◽  
Melting Temperatures ◽  
Liquid Phases ◽  
Dependent Potential ◽  
Higher Temperature ◽  
Induction Times ◽  
Dynamics Simulations

Molecular-dynamics simulations are used for examining the microscopic details of the homogeneous melting of benzene phase I. The equilibrium melting temperatures of our model were initially determined using the direct-coexistence method. Homogeneous melting at a higher temperature is achieved by heating a defect- and surfacefree crystal. The temperature-dependent potential energy and lattice parameters do not indicate a premelting phase even under superheated conditions. Further, statistical analyses using induction times computed from 200 melting trajectories were conducted, denoting that the homogeneous melting of benzene occurs stochastically, and that there is no intermediate transient state between the crystal and liquid phases. Additionally, the critical nucleus size is estimated using the seeding approach, along with the local bond order parameter. We found that the large diffusive motion arising from defect migration or neighbor-molecule swapping is of little importance during nucleation. Instead, the orientational disorder activated using the flipping motion of the benzene plane results in the melting nucleus.

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