Microscopic Properties of Point Defect and its Cluster in Delta-Phase Plutonium: A Molecular Dynamics Study

Self-irradiation effect induced by Pu α decay is an important influencing factor for long-term storage of Pu-based materials. In order to reveal the collision displacement cascade for uranium recoil nucleus induced by alpha decay in delta-phase plutonium at atomic level, we review the recent progress in self-irradiation of metallic plutonium and its alloys. We perform a molecular dynamics (MD) calculation on basis of modified embedded atom (MEAM) interatomic potentials, and obtain the minimum of displacement threshold energy (MDTE) for {1 1 1} lattice direction and microscopic evolution of He self-interstitial cluster. These findings are in agreement with previous experimental and theoretical results, and can be viewed as an essential input parameter for mesoscopic simulation to obtain the evolution of microscopic configuration at longer time and space, and might be also helpful for understanding the nucleation and growth mechanisms for vacancy and/or self-interstitial and its clusters, He-vacancy cluster and He bubbles in delta-phase plutonium and its alloys.

Download Full-text

Anisotropic Displacement Threshold Energies in Silicon by Molecular Dynamics Simulations

MRS Proceedings ◽

10.1557/proc-209-171 ◽

1990 ◽

Vol 209 ◽

Cited By ~ 2

Author(s):

LeAnn A. Miller ◽

David K. Brice ◽

Anil K. Prinja ◽

S. Thomas Picraux

Keyword(s):

Molecular Dynamics ◽

Theoretical Model ◽

Molecular Dynamics Simulations ◽

Radiation Effects ◽

Threshold Energy ◽

Molecular Beam Epitaxial ◽

Displacement Threshold ◽

Dynamics Simulations ◽

Molecular Beam Epitaxial Growth ◽

Threshold Energies

AbstractA combination of molecular dynamics simulations and theoretical modeling was used to examine the orientation dependent threshold energies for displacement of silicon atoms from their lattice site due to energetic particle collisions. These results are important for a detailed understanding of both radiation effects in silicon devices and beam-enhanced stimulation of molecular beam epitaxial growth.The molecular dynamics code developed for this study, which employs a Tersoff interaction potential, as well as the theoretical model that incorporates the symmetry of the crystal are described.Bulk displacement threshold energies were determined by the molecular dynamics code for four directions through the open face in the <111>. These values were then incorporated into the theoretical model for the average bulk displacement threshold energy. The average bulk displacement threshold energy was found to be 14.8 eV in 30° about <111> and 11.1 eV in 20° about <100>.

Download Full-text

Effects of vacancies on atom displacement threshold energy calculations through Molecular Dynamics Methods in BaTiO 3

Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment ◽

10.1016/j.nima.2016.07.056 ◽

2017 ◽

Vol 865 ◽

pp. 144-147 ◽

Cited By ~ 1

Author(s):

Eduardo Gonzalez Lazo ◽

Carlos M. Cruz Inclán ◽

Arturo Rodríguez Rodríguez ◽

Fernando Guzmán Martínez ◽

Yamiel Abreu Alfonso ◽

...

Keyword(s):

Molecular Dynamics ◽

Threshold Energy ◽

Energy Calculations ◽

Displacement Threshold ◽

Molecular Dynamics Methods ◽

Atom Displacement

Download Full-text

Anisotropy of damage productions in electron irradiated molybdenum

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010891x ◽

1978 ◽

Vol 36 (1) ◽

pp. 354-355

Author(s):

K. Izui ◽

S. Furuno ◽

H. Otsu ◽

T. Nishida ◽

H. Maeta

Keyword(s):

Electron Flux ◽

Threshold Energy ◽

High Energy ◽

Voltage Electron ◽

High Voltage Electron Microscope ◽

Displacement Threshold ◽

The Mean ◽

Channeling Effect ◽

Different Origins ◽

Threshold Energies

Anisotropy of damage productions in crystals due to high energy electron bombardment are caused from two different origins. One is an anisotropic displacement threshold energy, and the other is an anisotropic distribution of electron flux near the atomic rows in crystals due to the electron channeling effect. By the n-beam dynamical calculations for germanium and molybdenum we have shown that electron flux at the atomic positions are from ∽4 to ∽7 times larger than the mean incident flux for the principal zone axis directions of incident 1 MeV electron beams, and concluded that such a locally increased electron flux results in an enhanced damage production. The present paper reports the experimental evidence for the enhanced damage production due to the locally increased electron flux and also the results of measurements of the displacement threshold energies for the <100>,<110> and <111> directions in molybdenum crystals by using a high voltage electron microscope.

Download Full-text

Displacement threshold energy change in uniform stress fields

physica status solidi (b) ◽

10.1002/pssb.2221350250 ◽

1986 ◽

Vol 135 (2) ◽

pp. K113-K117

Author(s):

V. V. Kirsanov ◽

E. M. Kislitsina

Keyword(s):

Threshold Energy ◽

Energy Change ◽

Stress Fields ◽

Uniform Stress ◽

Displacement Threshold

Download Full-text

On the impact of lattice parameter accuracy of atomistic simulations on the microstructure of Ni-Ti shape memory alloys

Modelling and Simulation in Materials Science and Engineering ◽

10.1088/1361-651x/ac3b9e ◽

2021 ◽

Author(s):

Lorenzo La Rosa ◽

Francesco Maresca

Keyword(s):

Molecular Dynamics ◽

Shape Memory Alloys ◽

Shape Memory ◽

Shape Memory Effect ◽

Memory Effect ◽

Lattice Parameter ◽

Lattice Parameters ◽

Atomistic Simulations ◽

Interatomic Potentials ◽

The Impact

Abstract Ni-Ti is a key shape memory alloy (SMA) system for applications, being cheap and having good mechanical properties. Recently, atomistic simulations of Ni-Ti SMAs have been used with the purpose of revealing the nano-scale mechanisms that control superelasticity and the shape memory effect, which is crucial to guide alloying or processing strategies to improve materials performance. These atomistic simulations are based on molecular dynamics modelling that relies on (empirical) interatomic potentials. These simulations must reproduce accurately the mechanism of martensitic transformation and the microstructure that it originates, since this controls both superelasticity and the shape memory effect. As demonstrated by the energy minimization theory of martensitic transformations [Ball, James (1987) Archive for Rational Mechanics and Analysis, 100:13], the microstructure of martensite depends on the lattice parameters of the austenite and the martensite phases. Here, we compute the bounds of possible microstructural variations based on the experimental variations/uncertainties in the lattice parameter measurements. We show that both density functional theory and molecular dynamics lattice parameters are typically outside the experimental range, and that seemingly small deviations from this range induce large deviations from the experimental bounds of the microstructural predictions, with notable cases where unphysical microstructures are predicted to form. Therefore, our work points to a strategy for benchmarking and selecting interatomic potentials for atomistic modelling of shape memory alloys, which is crucial to modelling the development of martensitic microstructures and their impact on the shape memory effect.

Download Full-text

Comparative Studies on Water Self-Diffusivity Confined in Graphene Nanogap: Molecular Dynamics Simulation

ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels ◽

10.1115/icnmm2016-7962 ◽

2016 ◽

Author(s):

Mohammad Moulod ◽

Gisuk Hwang

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulation ◽

Surface Energy ◽

Water Transport ◽

Surface Interactions ◽

Bulk Water ◽

Water Desalination ◽

Atomic Scale ◽

Dynamics Simulation ◽

Interatomic Potentials

Fundamental understanding of the water in graphene is crucial to optimally design and operate the sustainable energy, water desalination, and bio-medical systems. A numerous atomic-scale studies have been reported, primarily articulating the surface interactions (interatomic potentials) between the water and graphene. However, a systematic comparative study among the various interatomic potentials is rare, especially for the water transport confined in the graphene nanostructure. In this study, the effects of different interatomic potentials and gap sizes on water self-diffusivity are investigated using the molecular dynamics simulation at T = 300 K. The water is confined in the rigid graphene nanogap with the various gap sizes Lz = 0.7 to 4.17 nm, using SPC/E and TIP3P water models. The water self-diffusivity is calculated using the mean squared displacement approach. It is found that the water self-diffusivity in the confined region is lower than that of the bulk water, and it decreases as the gap size decreases and the surface energy increases. Also, the water self-diffusivity nearly linearly decreases with the increasing surface energy to reach the bulk water self-diffusivity at zero surface energy. The obtained results provide a roadmap to fundamentally understand the water transport properties in the graphene geometries and surface interactions.

Download Full-text

Parallel Molecular Dynamics with Irregular Domain Decomposition

Communications in Computational Physics ◽

10.4208/cicp.140810.021210a ◽

2011 ◽

Vol 10 (4) ◽

pp. 1071-1088 ◽

Cited By ~ 8

Author(s):

Mauro Bisson ◽

Massimo Bernaschi ◽

Simone Melchionna

Keyword(s):

Molecular Dynamics ◽

Blood Flow ◽

Input Parameter ◽

Complex Geometries ◽

Irregular Domain ◽

Irregular Domains ◽

Additional Input ◽

Parallel Molecular Dynamics ◽

Dynamics Simulations ◽

General Method

AbstractThe spatial domain of Molecular Dynamics simulations is usually a regular box that can be easily divided in subdomains for parallel processing. Recent efforts aimed at simulating complex biological systems, like the blood flow inside arteries, require the execution of Parallel Molecular Dynamics (PMD) in vessels that have, by nature, an irregular shape. In those cases, the geometry of the domain becomes an additional input parameter that directly influences the outcome of the simulation. In this paper we discuss the problems due to the parallelization of MD in complex geometries and show an efficient and general method to perform MD in irregular domains.

Download Full-text