Journal ArticleDOI
Hydrogen in tungsten: Absorption, diffusion, vacancy trapping, and decohesion
TLDR
In this article, the authors report results from periodic density-functional theory calculations for three crucial aspects of this interaction: surface-to-subsurface diffusion of H into W, trapping of H at vacancies, and Henhanced decohesion, with a view to assess the likely extent of hydrogen isotope incorporation into tungsten reactor walls.Abstract:
Understanding the interaction between atomic hydrogen and solid tungsten is important for the development of fusion reactors in which proposed tungsten walls would be bombarded with high energy particles including hydrogen isotopes. Here, we report results from periodic density-functional theory calculations for three crucial aspects of this interaction: surface-to-subsurface diffusion of H into W, trapping of H at vacancies, and H-enhanced decohesion, with a view to assess the likely extent of hydrogen isotope incorporation into tungsten reactor walls. We find energy barriers of (at least) 2.08 eV and 1.77 eV for H uptake (inward diffusion) into W(001) and W(110) surfaces, respectively, along with very small barriers for the reverse process (outward diffusion). Although H dissolution in defect-free bulk W is predicted to be endothermic, vacancies in bulk W are predicted to exothermically trap multiple H atoms. Furthermore, adsorbed hydrogen is predicted to greatly stabilize W surfaces such that decohesion (fracture) may result from high local H concentrations.read more
Citations
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Journal ArticleDOI
Quantum effect on thermally activated glide of dislocations.
TL;DR: This work found a large decrease of the kink-pair formation enthalpy due to the quantization of the crystal vibrational modes, which means that the flow stress predicted by Orowan's law is strongly reduced when compared with its classical approximation and in much closer agreement with experiments.
Journal ArticleDOI
Review of hydrogen retention in tungsten
TL;DR: In this article, the authors aim at the clarification of the H retention mechanisms with critical review of reported data and presentation of recent results, and present a detailed review of the available data.
Journal ArticleDOI
Hydrogen diffusion and vacancies formation in tungsten: Density Functional Theory calculations and statistical models
TL;DR: In this paper, the authors investigated the interaction of hydrogen with tungsten by means of the density functional theory (DFT) and statistical methods based on the transition-state theory and thermodynamics, and concluded that the discrepancy existing between the experimental diffusion coefficient measured by Frauenfelder (1969) and the one calculated by DFT would be reconciled provided one uses two different diffusion regimes that would depend on temperature and vacancies concentration.
Journal ArticleDOI
A review of modelling and simulation of hydrogen behaviour in tungsten at different scales
TL;DR: In this article, the authors reviewed the recent findings regarding the behavior of H isotopes in W obtained via modelling and simulation at different scales, including dissolution, diffusion, accumulation and bubble formation.
Journal ArticleDOI
Interplay between hydrogen and vacancies in α -Fe
Erin Hayward,Chu-Chun Fu +1 more
TL;DR: In this paper, an atomistic study of the behavior and interactions of hydrogen and vacancies in body centered cubic (bcc) iron is presented, using both ab initio and classical molecular dynamics methods.
References
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Journal ArticleDOI
Generalized Gradient Approximation Made Simple
TL;DR: A simple derivation of a simple GGA is presented, in which all parameters (other than those in LSD) are fundamental constants, and only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked.
Journal ArticleDOI
Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set.
Georg Kresse,Jürgen Furthmüller +1 more
TL;DR: An efficient scheme for calculating the Kohn-Sham ground state of metallic systems using pseudopotentials and a plane-wave basis set is presented and the application of Pulay's DIIS method to the iterative diagonalization of large matrices will be discussed.
Journal ArticleDOI
Projector augmented-wave method
TL;DR: An approach for electronic structure calculations is described that generalizes both the pseudopotential method and the linear augmented-plane-wave (LAPW) method in a natural way and can be used to treat first-row and transition-metal elements with affordable effort and provides access to the full wave function.
Journal ArticleDOI
From ultrasoft pseudopotentials to the projector augmented-wave method
Georg Kresse,Daniel P. Joubert +1 more
TL;DR: In this paper, the formal relationship between US Vanderbilt-type pseudopotentials and Blochl's projector augmented wave (PAW) method is derived and the Hamilton operator, the forces, and the stress tensor are derived for this modified PAW functional.
Journal ArticleDOI
Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set
Georg Kresse,Jürgen Furthmüller +1 more
TL;DR: A detailed description and comparison of algorithms for performing ab-initio quantum-mechanical calculations using pseudopotentials and a plane-wave basis set is presented in this article. But this is not a comparison of our algorithm with the one presented in this paper.