Self-Interstitial Configuration in B.C.C. Metals. An Analysis Based on Many-Body Potentials for Fe and Mo

Simonelli, G.; Pasianot, R.C.; Savino, E. J.

doi:10.1002/(sici)1521-3951(200002)217:2<747::aid-pssb747>3.0.co;2-5

Cited by 20 publications

(6 citation statements)

References 31 publications

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“…The prediction that the ͗111͘ dumbbell is the most stable interstitial configuration is at variance with the widely accepted view that the ͗110͘-dumbbell is the equilibrium interstitial in bcc metals 1,[6][7][8]20 . Previous calculations, however, were based upon embedded-atom-method ͑EAM͒ potentials fitted to reproduce equilibrium bulk properties.…”

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confidence: 72%

“…Unfortunately, atomistic simulations based upon different empirical potentials yield widely disparate predictions for self-interstitials in body-centered cubic ͑bcc͒ metals. [6][7][8] While ab initio calculations can, in principle, alleviate this uncertainty, such calculations of interstitial properties have been very rare. 9 This is, in part, because atomatom separations in the vicinity of interstitials are small compared with the equilibrium interatomic distance and very large simulation cells are required to account for the accompanying large relaxations.…”

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confidence: 99%

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Self-interstitials in V and Mo

et al. 2002

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We report an extensive ab initio study of self-interstitials in V and Mo. Contrary to the widely accepted picture, the ͗111͘ dumbbell is found to be the most stable structure. The activated state for migration is the crowdion configuration, with an extremely low barrier (ϳ0.01 eV), suggesting 1d ͑one-dimensional͒ diffusion at low temperatures and 3d diffusion at high temperature. In the case of Mo, the energy landscape between the ͗111͘ and ͗110͘ dumbbells is very shallow. Predicted migration energies and self-interstitial structures are consistent with experiment.

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confidence: 72%

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Self-interstitials in V and Mo

et al. 2002

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“…Atomistic simulations based on semiempirical potentials appeared equally inconclusive, with some simulations predicting the ͗110͘ dumbbell while others predicting the ͗111͘ crowdion as the lowest-energy configuration of a self-interstitial atom defect. [22][23][24][25][26] Large-scale density-functional calculations performed in the last several years provided significantly more reliable and largely free from model assumptions information about the energies of formation of stable, as well as metastable, configurations of self-interstitial atom defects. These configurations, illustrated in Fig.…”

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confidence: 99%

Multiscale modeling of crowdion and vacancy defects in body-centered-cubic transition metals

2007

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We investigate the structure and mobility of single self-interstitial atom and vacancy defects in bodycentered-cubic transition metals forming groups 5B ͑vanadium, niobium, and tantalum͒ and 6B ͑chromium, molybdenum, and tungsten͒ of the Periodic Table. Density-functional calculations show that in all these metals the axially symmetric ͗111͘ self-interstitial atom configuration has the lowest formation energy. In chromium, the difference between the energies of the ͗111͘ and the ͗110͘ self-interstitial configurations is very small, making the two structures almost degenerate. Local densities of states for the atoms forming the core of crowdion configurations exhibit systematic widening of the "local" d band and an upward shift of the antibonding peak. Using the information provided by electronic structure calculations, we derive a family of Finnis-Sinclair-type interatomic potentials for vanadium, niobium, tantalum, molybdenum, and tungsten. Using these potentials, we investigate the thermally activated migration of self-interstitial atom defects in tungsten. We rationalize the results of simulations using analytical solutions of the multistring Frenkel-Kontorova model describing nonlinear elastic interactions between a defect and phonon excitations. We find that the discreteness of the crystal lattice plays a dominant part in the picture of mobility of defects. We are also able to explain the origin of the non-Arrhenius diffusion of crowdions and to show that at elevated temperatures the diffusion coefficient varies linearly as a function of absolute temperature.

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“…In comparison with the regular EAM, the EDM contains only one additional adjustable parameter, G. Like the EAM, the EDM is based on cutoff functions and does not involve any screening procedure. [21,[23][24][25] A number of specific, usually angular-dependent, interatomic potentials have been constructed for silicon, carbon, and other semiconductor [21,[23][24][25] A number of specific, usually angular-dependent, interatomic potentials have been constructed for silicon, carbon, and other semiconductor…”

Section: Angular-dependent Potentialsmentioning

confidence: 99%

Atomistic Computer Simulation of Diffusion

Mishin

2005

Diffusion Processes in Advanced Technological Materials

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The past decades have seen a tremendous increase in the application of computer modeling and simulation methods to diffusion processes in materials. Along with continuum modeling aimed at describing diffusion processes by differential equations, atomic-level modeling is playing an increasingly important role as a means of gaining fundamental insights into diffusion phenomena.One of the reasons for the growing interest in the atomistic modeling of diffusion is the recognition that experimental methods only deliver effective diffusion coefficients, i.e., coefficients averaged over the diffusion zone and over many atomic jumps contributing to the diffusion flux. Recovering information relating to individual diffusion mechanisms, their activation barriers, correlation factors, and other atomic-level characteristics is extremely difficult, if not impossible. As a result, many experimental measurements produce useful reference numbers for handbooks and immediate technological applications (which is very important too) but do not add much to our basic understanding of diffusion processes. In the long run, however, it is highly desirable to be able to predict diffusion coefficients by calculation. This ability is critical for the ongoing effort to reduce the dramatic costs associated with the development of new technologically advanced materials by the traditional empirical approach. Atomistic modeling appears to offer the only viable way of gaining insights into mechanisms of complex diffusion processes and thus creating a fundamental framework for predictive diffusion calculations.A second reason for this growing interest is that drastically increased computer speeds have enabled computer simulations that could only be dreamed about just two decades ago. New methods have been developed that provide a realistic description of atomic interactions in materials, accelerate molecular dynamics (MD) and Monte Carlo simulations, and allow more reliable calculations of transition rates. The new methods provide

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Self-Interstitial Configuration in B.C.C. Metals. An Analysis Based on Many-Body Potentials for Fe and Mo

Cited by 20 publications

References 31 publications

Self-interstitials in V and Mo

Self-interstitials in V and Mo

Multiscale modeling of crowdion and vacancy defects in body-centered-cubic transition metals

Atomistic Computer Simulation of Diffusion

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