scholarly journals Atomistic and Kinetic Simulations of Radiation Damage in Molybdenum

2012 ◽  
Vol 1444 ◽  
Author(s):  
Zeke Insepov ◽  
Jeffrey Rest ◽  
Abdellatif M. Yacout ◽  
Bei Ye ◽  
Di Yun ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Quantum Mechanics ◽  
Ab Initio ◽  
Time Evolution ◽  
Rate Constants ◽  
Diffusion Coefficients ◽  
Radiation Defects ◽  
Dislocation Loops ◽  
Kinetic Coefficients ◽  
Small Clusters

ABSTRACTA new Mo potential, developed recently by using an ab initio quantum mechanics theory, was used to study formation and time evolution of radiation defects, such as self-interstitial atoms (SIAs), vacancies, and small clusters of SIAs, using molecular dynamics (MD). MD models were developed for calculation of the diffusion coefficients of vacancies, self-interstitials, and small dislocation loops containing 2 to 37 SIAs; and the rate constants were calculated. Interactions of small SIA loops with SIAs were simulated. The results show that rotation of SIA from one <111> to another equivalent direction is an important mechanism that significantly contributes to kinetic coefficients.

scholarly journals Computational Methods for Ab Initio Molecular Dynamics

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Eric Paquet ◽  
Herna L. Viktor
Keyword(s):  
Molecular Dynamics ◽  
Quantum Mechanics ◽  
Ab Initio ◽  
First Principles ◽  
Density Functional ◽  
Path Integrals ◽  
Ab Initio Molecular Dynamics ◽  
Molecular Systems ◽  
Hartree Fock ◽  
Computational Perspective

Ab initio molecular dynamics is an irreplaceable technique for the realistic simulation of complex molecular systems and processes from first principles. This paper proposes a comprehensive and self-contained review of ab initio molecular dynamics from a computational perspective and from first principles. Quantum mechanics is presented from a molecular dynamics perspective. Various approximations and formulations are proposed, including the Ehrenfest, Born–Oppenheimer, and Hartree–Fock molecular dynamics. Subsequently, the Kohn–Sham formulation of molecular dynamics is introduced as well as the afferent concept of density functional. As a result, Car–Parrinello molecular dynamics is discussed, together with its extension to isothermal and isobaric processes. Car–Parrinello molecular dynamics is then reformulated in terms of path integrals. Finally, some implementation issues are analysed, namely, the pseudopotential, the orbital functional basis, and hybrid molecular dynamics.

Ab Initio Molecular Dynamics of Column IV Microclusters

1990 ◽  
Vol 193 ◽  
Author(s):  
David A. Drabold ◽  
Stefan Klemm ◽  
Otto F. Sankey
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Molecular Dynamics Simulations ◽  
Vibrational Spectra ◽  
Ground State ◽  
Spectral Estimation ◽  
Ab Initio Molecular Dynamics ◽  
Estimation Technique ◽  
Dynamics Simulations ◽  
Small Clusters

ABSTRACTWe report the results of ab-initio molecular dynamics simulations for small clusters of Si and C atoms. Ground-state geometries and vibrational spectra are presented. We also describe a Bayesian spectral estimation technique which we have found to be useful in analyzing molecular dynamics trajectories.

scholarly journals Diffusion of lithium ions in Lithium-argyrodite solid-state electrolytes

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Ardeshir Baktash ◽  
James C. Reid ◽  
Tanglaw Roman ◽  
Debra J. Searles
Keyword(s):  
Molecular Dynamics ◽  
Solid State ◽  
Ab Initio ◽  
Molecular Dynamics Simulations ◽  
Diffusion Coefficients ◽  
Ab Initio Molecular Dynamics ◽  
Nonequilibrium Molecular Dynamics ◽  
Lithium Ions ◽  
Solid State Electrolytes ◽  
Dynamics Simulations

Abstract The use of solid-state electrolytes to provide safer, next-generation rechargeable batteries is becoming more feasible as materials with greater stability and higher ionic diffusion coefficients are designed. However, accurate determination of diffusion coefficients in solids is problematic and reliable calculations are highly sought-after to understand how their structure can be modified to improve their performance. In this paper we compare diffusion coefficients calculated using nonequilibrium and equilibrium ab initio molecular dynamics simulations for highly diffusive solid-state electrolytes, to demonstrate the accuracy that can be obtained. Moreover, we show that ab initio nonequilibrium molecular dynamics can be used to determine diffusion coefficients when the diffusion is too slow for it to be feasible to obtain them using ab initio equilibrium simulations. Thereby, using ab initio nonequilibrium molecular dynamics simulations we are able to obtain accurate estimates of the diffusion coefficients of Li ions in Li6PS5Cl and Li5PS4Cl2, two promising electrolytes for all-solid-state batteries. Furthermore, these calculations show that the diffusion coefficient of lithium ions in Li5PS4Cl2 is higher than many other potential all-solid-state electrolytes, making it promising for future technologies. The reasons for variation in conductivities determined using computational and experimental methods are discussed. It is demonstrated that small degrees of disorder and vacancies can result in orders of magnitude differences in diffusivities of Li ions in Li6PS5Cl, and these factors are likely to contribute to inconsistencies observed in experimentally reported values. Notably, the introduction of Li-vacancies and disorder can enhance the ionic conductivity of Li6PS5Cl.

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