Comparative analysis of the electronic structures of mono- and bi-atomic chains of IV, III–V and II–VI group elements calculated using the DFT LCAO and LACW methods

D’yachkov, P. N.; Zaluev, V. A.; Piskunov, Sergei; Zhukovskii, Yuri F.

doi:10.1039/c5ra16168a

“…The calculated results of the bond lengths of B–N, Au–B, and Au–N for each equilibrium structure are shown in Table . It is observed from Table that the characteristics of the bond length oscillation are similar to the carbon atom chains with different lengths and terminations. − The average bond lengths of the B–N bonds are 1.267, 1.298, 1.302, and 1.303 Å, respectively, which are in good agreement with the theoretical and experimental results (1.300 and 1.310 Å) ,− as the length increases. It can be seen from Table that the optimized structures are almost symmetric about the center of the molecular chain, which is similar to the covalent coupling of the carbon monoatomic chain with Au electrodes. , Also, the short and long B–N bonds alternatively appear in the linear chains.…”

Section: Results and Discussionsupporting

confidence: 77%

Electron Transport of the Nanojunctions of (BN)_n (n = 1–4) Linear Chains: A First-Principles Study

Zhao

¹

,

Lan

²

,

Hu

³

et al. 2021

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We applied the density functional theory and nonequilibrium Green's function method (DFT + NEGF) to investigate the relationship between the conductance and chain length in the stretching process, the asymmetric coupling of contact points, and the influence of positive and negative biases on the electron transport properties of the nanojunctions formed by the coupling of (BN) n (n = 1−4) linear chains and Au(100)-3 × 3 semi-infinite electrodes. We find that the BN junction has the lowest stability and the (BN) 2 junction has the highest stability. Under zero bias, the equilibrium conductance decreases as the chain length increases; p x and p y orbitals play a leading role in electron transport. In the bias range of −1.6 to 1.6 V, the current of the (BN) n (n = 1−4) linear chains increases linearly with increasing voltage. Under the same bias voltage, (BN) 1 has the largest current, so its electron transport property is the best. The rectification effect reflects the asymmetry of the structure of BN linear chains themselves and the asymmetry of coupling with the Au electrode surfaces at both ends. With the chain length increasing, the transmission spectrum near E f is suppressed, the tunneling current decreases, and the rectification ratio increases. (BN) 4 molecular junctions have the largest rectification ratio, reaching 13.32 when the bias voltage is 1.6 V. Additionally, the Au−N strong coupling is more conducive to the electron transport of the molecular chain than the Au−B weak coupling. Our calculations provide an important theoretical reference for the design and development of BN linear-chain nanodevices.

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“…The linearized augmented cylindrical wave (LACW) technique is an extension of the linearized augmented plane-wave (LAPW) method to the specific case of one-dimensional cylindrical or tubular polyatomic systems such as the WS 2 nanotubes studied here (Figure ). The main foundations and applications of the LACW method have been described in detail elsewhere − and are compiled in a recent review . Similar to the simple version of the original LAPW theory for bulk materials, the LACW method is based on the muffin-tin (MT) and the local density exchange approximation for the electronic potential.…”

Section: Computational Detailsmentioning

confidence: 99%

First-Principles Evaluation of the Morphology of WS₂ Nanotubes for Application as Visible-Light-Driven Water-Splitting Photocatalysts

Piskunov

¹

,

Lisovski

²

,

Zhukovskii

³

et al. 2019

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One-dimensional tungsten disulfide (WS 2 ) single-walled nanotubes (NTs) with either achiral, i.e., armchair ( n , n ) and zigzag-type ( n , 0), or chiral (2 n , n ) configuration with diameters d NT > 1.9 nm have been found to be suitable for photocatalytic applications, since their band gaps correspond to the frequency range of visible light between red and violet (1.5 eV < Δε gap < 2.6 eV). We have simulated the electronic structure of nanotubes with diameters up to 12.0 nm. The calculated top of the valence band and the bottom of the conduction band (ε VB and ε CB , respectively) have been properly aligned relatively to the oxidation (ε O 2 /H 2 O ) and reduction (ε H 2 /H 2 O ) potentials of water. Very narrow nanotubes (0.5 < d NT < 1.9 nm) are unsuitable for water splitting because the condition ε VB < ε O 2 /H 2 O < ε H 2 /H 2 O < ε CB does not hold. For nanotubes with d NT > 1.9 nm, the condition ε VB < ε O 2 /H 2 O < ε H 2 /H 2 O < ε CB is fulfilled. The values of ε VB and ε CB have been found to depend only on the diameter and not on the chirality index of the nanotube. The reported structural and electronic properties have been obtained from either hybrid density functional theory and Hartree–Fock linear combination of atomic orbitals calculations (using the HSE06 functional) or the linear augmented cylindrical waves density functional theory method. In addition to single-walled NTs, we have investigated a number of achiral double-walled ( m , m )@( n , n ) and ( m , 0)@( n , 0) as well as triple-walled ( l , l )@( m , m )@( n , n ) and ( l , 0)@( m , 0)@( n , 0) nanotubes. All multiwalled nanotubes show a common dependence of their band gap on the diameter of the inner nanotube, independent of chirality index and number of walls. This behavior of WS ...

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“…The associated AC is known to be smoothly deformed through the energies and electronegativities of the AOs in the corresponding limit. 31 This suggests it may be possible to obtain control over band flatness in similar parity-enforced ACs such as those found in H 3 S, i.e., a pathway to f lat band engineering. But the Γ-H-N hypersurface on which we showed the flat-band region to appear in H 3 S is 2D, not 1D − this makes things more complicated.…”

Section: ■ Results and Discussionmentioning

confidence: 96%

“…For that case, the generating pair is bold-scriptB normalD ∞ normalh = {Γ, Χ}. The associated AC is known to be smoothly deformed through the energies and electronegativities of the AOs in the corresponding limit . This suggests it may be possible to obtain control over band flatness in similar parity-enforced ACs such as those found in H 3 S, i.e., a pathway to flat band engineering .…”

Section: Results and Discussionmentioning

confidence: 99%

Symmetry-Shaped Singularities in High-Temperature Superconductor H₃S

Thomsen,

Goesten

2024

J. Am. Chem. Soc.

1

0

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The superconducting critical temperature of H 3 S ranks among the highest measured, at 203 K. This impressive value stems from a singularity in the electronic density-of-states, induced by a flat-band region that consists of saddle points. The peak sits right at the Fermi level, so that it gives rise to a giant electron− phonon coupling constant. In this work, we show how atomic orbital interactions and space group symmetry work in concert to shape the singularity. The body-centered cubic Brillouin Zone offers a unique 2D hypersurface in reciprocal space: fully connecting squares with two different high-symmetry points at the corners, Γ and H, and a third one in the center, N. Orbital mixing leads to the collapse of fully connected 1D saddle point lines around the square centers, due to a symmetry-enforced s-p energy inversion between Γ and H. The saddle-point states are invariably nonbonding, which explains the unconventionally weak response of the superconductor's critical temperature to pressure. Although H 3 S appears to be a unique case, the theory shows how it is possible to engineer flat bands and singularities in 3D lattices through symmetry considerations.

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Comparative analysis of the electronic structures of mono- and bi-atomic chains of IV, III–V and II–VI group elements calculated using the DFT LCAO and LACW methods

Abstract: Ab initio non-relativistic LCAO and relativistic LACW methods are used to calculate the electronic properties of the covalent and partially ionic ANB8−N atomic chains. Their band structures are found to be markedly different when using both methods.

Cited by 7 publications

References 50 publications

Electron Transport of the Nanojunctions of (BN)_n (n = 1–4) Linear Chains: A First-Principles Study

Electron Transport of the Nanojunctions of (BN)_n (n = 1–4) Linear Chains: A First-Principles Study

First-Principles Evaluation of the Morphology of WS₂ Nanotubes for Application as Visible-Light-Driven Water-Splitting Photocatalysts

Symmetry-Shaped Singularities in High-Temperature Superconductor H₃S

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Comparative analysis of the electronic structures of mono- and bi-atomic chains of IV, III–V and II–VI group elements calculated using the DFT LCAO and LACW methods

Abstract: Ab initio non-relativistic LCAO and relativistic LACW methods are used to calculate the electronic properties of the covalent and partially ionic ANB8−N atomic chains. Their band structures are found to be markedly different when using both methods.

Cited by 7 publications

References 50 publications

Electron Transport of the Nanojunctions of (BN)n (n = 1–4) Linear Chains: A First-Principles Study

Electron Transport of the Nanojunctions of (BN)n (n = 1–4) Linear Chains: A First-Principles Study

First-Principles Evaluation of the Morphology of WS2 Nanotubes for Application as Visible-Light-Driven Water-Splitting Photocatalysts

Symmetry-Shaped Singularities in High-Temperature Superconductor H3S

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Electron Transport of the Nanojunctions of (BN)_n (n = 1–4) Linear Chains: A First-Principles Study

Electron Transport of the Nanojunctions of (BN)_n (n = 1–4) Linear Chains: A First-Principles Study

First-Principles Evaluation of the Morphology of WS₂ Nanotubes for Application as Visible-Light-Driven Water-Splitting Photocatalysts

Symmetry-Shaped Singularities in High-Temperature Superconductor H₃S