Development of a tight-binding model for Cu and its application to a Cu-heat-sink under irradiation

Ding, Wenyi; He, Hong; Pan, Bicai

doi:10.1007/s10853-015-9097-7

Cited by 21 publications

(7 citation statements)

References 52 publications

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“…Empirically fitting hopping integrals to a screening function is a method which has been used successfully for a range of systems including Cu, C, Mo, and Ge [57][58][59][60][61]. Particularly relevant is the work on Ge where reasonable defect energies were obtained despite only fitting to perfect crystal structures [58]: e.g., the vacancy formation energy was 2.82 eV compared to 2.42 eV from DFT.…”

Section: Discussionmentioning

confidence: 99%

Systematic development of ab initio tight-binding models for hexagonal metals

Smutna

Fogarty

Wenman

et al. 2020

Phys. Rev. Materials

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A systematic method for building an extensible tight-binding model from ab initio calculations has been developed and tested on two hexagonal metals: Zr and Mg. The errors introduced at each level of approximation are discussed and quantified. For bulk materials, using a limited basis set of spd orbitals is shown to be sufficient to reproduce with high accuracy bulk energy versus volume curves for fcc, bcc, and hcp lattice structures, as well as the electronic density of states. However, the two-center approximation introduces errors of several tenths of eV in the pair potential, crystal-field terms, and hopping integrals. Environmentally dependent corrections to the former two have been implemented, significantly improving the accuracy. Two-center hopping integrals were corrected by taking many-center hopping integrals for a set of structures of interest, rotating them into the bond reference frame, and then fitting a smooth function through these values. Finally, a pair potential was fitted to correct remaining errors. However, this procedure is not sufficient to ensure transferability of the model, especially when point defects are introduced. In particular, it is shown to be problematic when interstitial elements are added to the model, as demonstrated in the case of octahedral self-interstitial atoms.

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Section: Discussionmentioning

confidence: 99%

Systematic development of ab initio tight-binding models for hexagonal metals

Smutna

Fogarty

Wenman

et al. 2020

Phys. Rev. Materials

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“…Under this treatment, Equation () is transformed into

\begin{equation}\left( {H - {\varepsilon }_nS} \right){c}_n = 0\end{equation}

where H is the Hamiltonian matrix, S is the overlap matrix, and c n is the corresponding coefficient matrix. Similar to references, [ 39,48 ] the scheme of the orthogonal basis set is employed in the present work so that S in Equation () becomes a unit matrix. Based on the two‐center approximation proposed by Slater and Koster, [ 49 ] the hopping terms in the Hamiltonian matrix H can be expressed as a linear combination of related bond integrals V ll ′ m ( l and l' = s, p, d …; m = σ, π, δ …).…”

Section: Computation Methodsmentioning

confidence: 99%

Interplay between the Edge Dislocation and Hydrogen in Tungsten at Electronically Excited States

Wang

Ding

et al. 2023

Advanced Physics Research

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Under the continuous irradiation of high‐density and high‐energy photons from the plasma core of a fusion reactor, the plasma‐facing materials (PFMs) of tungsten (W) are in electronically excited states. How hydrogen (H) interacts with defective PFMs in an electronically excited state is an open question. The authors report the developed W‐H tight‐binding (TB) potential model and employ this model to systemically investigate the interaction between an edge dislocation in tungsten with H at different electronically excited states. With the enhancement of electronic excitation, the strong attraction of the dislocation core to H slightly fluctuates, while the attraction to H is significantly enhanced in the region outside the dislocation core. When the electronic excitation energy is ≈0.86 eV, the region of tensile stress can trap H without additional energy. Additionally, the electronic excitation simultaneously makes H migration easy. It is revealed that the transfer of partial energy of the excited electrons to the lattice leads to the nonthermal expansion of the system and affects the interaction between the edge dislocation and H. These results not only show the nonthermal effect of tuning the interaction between hydrogen and the edge dislocation in tungsten but also uncover the nature underlying these phenomena.

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“…In our TB potential model, the For W, we adopt the atomic orbital 5d6s6p as the basis. The expression and corresponding parameters of its bond integrals and the Coulomb terms have been reported in [49][50][51]. For the He system, we choose the 1s orbital as the atomic orbital basis set.…”

Section: W-he Tb Potential Modelmentioning

confidence: 99%

Microscopic mechanism of nucleation and growth of helium bubbles in monovacancy in tungsten: helium regulates the charged states of tungsten atoms

Wang

Pan

2023

Nucl. Fusion

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In fusion reactor, tungsten (W) has been selected as a candidate for plasma-facing materials (PFMs) due to its excellent properties. However, W-PFMs suffer from helium (He) bubbles where He atoms are produced during deuterium tritium fusion in fusion reactors. To date, there have been few contributions to uncovering the formation of He bubbles from the perspective of the microscopic electronic structure of He-mediated tungsten. In this work, we develop a tight-binding potential model for the W-He interaction to study He atom aggregation and nucleation in the electronic ground state as well as in different electronic excited states. The most important finding of this paper is that caused by the He atoms in the vacancy, some d-orbital electrons of the W atoms at the inner wall of the vacancy are transferred to the W atoms farther away from the vacancy, leading to the feature of positively charged W ions at the inner wall of the vacancy. As the number of He atoms in the vacancy increases, these W ions become more cationic. Under the repulsion between these adjacent cationic ions, the volume of vacancies increases, and more He atoms tend to gather and nucleate there. At the same time, the enhancement of the electronic excitation can also promote the abovementioned electron transfer between W atoms and further increase the vacancy volume, which increases the self-aggregation of the He atoms in the vacancy. Our results shed new light on understanding He self-aggregation in many different metal materials.

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Development of a tight-binding model for Cu and its application to a Cu-heat-sink under irradiation

Cited by 21 publications

References 52 publications

Systematic development of ab initio tight-binding models for hexagonal metals

Systematic development of ab initio tight-binding models for hexagonal metals

Interplay between the Edge Dislocation and Hydrogen in Tungsten at Electronically Excited States

Microscopic mechanism of nucleation and growth of helium bubbles in monovacancy in tungsten: helium regulates the charged states of tungsten atoms

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