A new empirical potential for simulating the formation of defects and their mobility in uranium dioxide

Morelon, N.-D.; Ghaleb, D.; Delaye, Jean‐Marc; Brutzel, L. Van

doi:10.1080/1478643031000091454

Cited by 164 publications

(195 citation statements)

References 40 publications

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“…6 with the corresponding experimental data. 27 The quality is similar to what is given by the previous potentials 26,28,29 as tabulated in the work by Morelon et al 26 To summarize, we have shown a methodology for developing an interatomic pair potential such that it is appropriate for all relevant interatomic separations, without the need for any ambiguous splines. Splining between regions of different characteristics is not just an inconvenience in the implementation of a potential in MD simulations but also introduces an uncertainty regarding which distances, and by which functions, one realizes the splines.…”

Section: ͑9͒supporting

confidence: 70%

Ab initioconstruction of interatomic potentials for uranium dioxide across all interatomic distances

2009

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We provide a methodology for generating interatomic potentials for use in classical molecular-dynamics simulations of atomistic phenomena occurring at energy scales ranging from lattice vibrations to crystal defects to high-energy collisions. A rigorous method to objectively determine the shape of an interatomic potential over all length scales is introduced by building upon a charged-ion generalization of the well-known ZieglerBiersack-Littmark universal potential that provides the short-and long-range limiting behavior of the potential. At intermediate ranges the potential is smoothly adjusted by fitting to ab initio data. Our formalism provides a complete description of the interatomic potentials that can be used at any energy scale, and thus, eliminates the inherent ambiguity of splining different potentials generated to study different kinds of atomic-materials behavior. We exemplify the method by developing rigid-ion potentials for uranium dioxide interactions under conditions ranging from thermodynamic equilibrium to very high atomic-energy collisions relevant for fission events. DOI: 10.1103/PhysRevB.80.174302 PACS number͑s͒: 31.15.es, 34.20.Cf, 61.82.Ms Molecular dynamics ͑MD͒ simulations provide a convenient tool for studying the dynamics of large atomic ensembles, provided that the dynamics of interest is not of a duration that makes the simulation time impractical. There are many examples of beautiful applications of how MD has been able to provide detailed insight into the dynamics and statistics of materials behavior. One contemporary interest is the field of high-energy radiation damage in crystalline materials, such as nuclear fuel. A core material of interest in this context is uranium dioxide and one of the important aspects of the interest in this material is to understand the evolution and statistics of atomic displacement cascades due to highenergy radiation. 1 Classical molecular dynamics is ideally suited for this kind of study since it strikes a fine balance between being coarse enough to simulate the spatial scale necessary to represent the extent of a damage cascade due to, e.g., a 100 MeV atomic collision with being detailed enough to retain the atomic structure of the material. The highenergy range of the potential ͑short range in atomic separation͒ is consistent with the well-accepted Ziegler-BiersackLittmark ͑ZBL͒ universal-pair potentials, 2 which treat closerange atomic interactions as screened Coulomb forces between the nuclei. However, the complexity of the true interatomic interactions cannot be fully represented in an efficient manner by a simple classical functional form. Thus, one needs to develop a set of essential interaction features that are necessary for a given application. This is a particularly challenging exercise for radiation damage simulations due to the disparate scales of energies involved. Therefore, interatomic potentials, suitable for this purpose, are typically constructed by smoothly joining different types of interactions. At medium to long-range dist...

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Section: ͑9͒supporting

confidence: 70%

Ab initioconstruction of interatomic potentials for uranium dioxide across all interatomic distances

2009

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“…We benchmark four empirical potentials versus DFT: Arima et al 24 , Tiwary et al 11 , Morelon et al 25 , and Basak et al 26 For notational simplicity, we refer to these potentials just by the names of the first authors of Refs 24, 11, 25, and 26.We find that the Basak and Morelon potentials compare favorably with density functional theory for the diffusion of a Schottky defect cluster so we use these potentials to calculate the XeTV diffusion barriers. For the xenon components of the potentials, we use the empirical potentials of Geng et al 27 and Chartier et al, 28 which have been created to add xenon interactions to the Basak and Morelon potentials, respectively.…”

Section: Introductionmentioning

confidence: 99%

Pathway and energetics of xenon migration in uranium dioxide

Thompson

Wolverton

2013

Phys. Rev. B

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Using a combination of Density Functional Theory (DFT), classical potentials, Molecular Dynamics (MD), and Nudged Elastic Band (NEB) calculations, we explore the diffusion of xenon in uranium dioxide (UO 2 ). We compare migration barriers of empirical potentials with DFT by performing NEB calculations and subsequently we use the DFT-validated empirical potentials to calculate vacancy clusters, with and without xenon, to determine the migration path and barrier of xenon in bulk UO 2 . We find (i) two empirical potentials out of four tested agree qualitatively with DFT derived energetics for Schottky defect migration, (ii) through the use of molecular dynamics with empirical potentials, we have found a new path for the diffusion of xenon-tetravacancy clusters (Xe + 2 V U + 2 V O ), (iii) this new path has an energy barrier significantly lower than previously reported paths by nearly 1 eV, (iv) we examine the physical contributions to the migration pathway and find the barrier is largely electrostatic and that xenon contributes very little to the barrier height, (v) once a uranium vacancy attaches to a xenonSchottky defect, the resulting xenon-tetravacancy cluster is strongly bound, and (vi) like xenon in a tetravacancy, a xenon-double Schottky defect can diffuse in a concerted manor with a comparable barrier to xenon in a tetravacancy, but two of the oxygen vacancies are only weakly bound to the defect.

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“…17,18 In this study, the interatomic interactions were described using a conventional rigid-ion potential. 19 This interatomic potential was primarily developed to simulate displacement cascades in a UO 2 matrix. Thus, it is supposed to describe correctly the experimental energies of formation and migration of point defects and the structural effects created by decelerating recoil nuclei in a UO 2 matrix.…”

Section: Introductionmentioning

confidence: 99%

Frenkel pair recombinations in UO2: Importance of explicit description of polarizability in core-shell molecular dynamics simulations

2012

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The oxygen and uranium Frenkel pair (FP) recombination mechanisms are studied in UO 2 using an empirical interatomic potential accounting for the polarizability of the ions, namely a dynamical core-shell model. The results are compared to a more conventional rigid-ion model. Both model types have been implemented into the CP2K program package and thoroughly validated. The overall picture indicates that the FP recombination mechanism is a complex process involving several phenomena. The FP recombination can happen instantaneously when the distance between the interstitial and the vacancy is small or can be thermally activated at larger separation distances. However, other criteria can prevail over the interstitial-vacancy distance. The surrounding environment of the FP defect, the mechanical stiffness of the matrix, and the orientation of the migration path are shown to be major factors acting on the FP lifetime. The core-shell and rigid-ion models provide a similar qualitative description of the FP recombination mechanism. However, the FP stabilities determined by both models significantly differ in the lower temperature range considered. Indeed, the recombination time of the oxygen and uranium FPs can be up to an order of magnitude lower in the core-shell model at T = 600 K and T = 1800 K, respectively. These differences highlight the importance of the explicit description of polarizability on some crucial properties such as the resistance to amorphization. This refined description of the interatomic interactions would certainly affect the description of the recrystallization process following a displacement cascade. In turn, the self-healing phase would be better accounted for in the core-shell model and the misestimate inherent to the lack of polarizability in the rigid-ion model corrected.

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A new empirical potential for simulating the formation of defects and their mobility in uranium dioxide

Cited by 164 publications

References 40 publications

Ab initioconstruction of interatomic potentials for uranium dioxide across all interatomic distances

Ab initioconstruction of interatomic potentials for uranium dioxide across all interatomic distances

Pathway and energetics of xenon migration in uranium dioxide

Frenkel pair recombinations in UO2: Importance of explicit description of polarizability in core-shell molecular dynamics simulations

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