Designing a family of 2D kagome monolayer B₁₈S₈, B₁₈S₈H₂, B₁₈S₆X₂ (X=Cl,Br,I) with tunable Dirac cones and high Fermi velocity
Pith reviewed 2026-05-15 17:59 UTC · model grok-4.3
The pith
Surface passivation and halogen substitution move the Dirac cone to the Fermi level in a family of 2D kagome boron-sulfur monolayers
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Through the '1+3' design strategy combined with surface passivation and charge balance, the authors create B18S8, B18S8H2, and B18S6X2 where X is Cl, Br, or I. These exhibit kagome lattice electronic structures. The unmodified B18S8 has its Dirac cone 1 eV above the Fermi level, but hydrogen passivation or halogen replacement brings it to the Fermi level. The resulting Fermi velocities reach 2.69 to 3.07 x 10^5 m/s, and including spin-orbit coupling opens bandgaps of 20 to 55 meV at the Dirac point.
What carries the argument
Surface hydrogen passivation or halogen atom substitution on the kagome boron-sulfur monolayer that shifts the Dirac cone position to the Fermi level while preserving high velocities.
Load-bearing premise
The density functional theory calculations used in the design accurately reflect the actual electronic band structures and velocities in these materials.
What would settle it
Synthesis of one of the proposed monolayers followed by angle-resolved photoemission spectroscopy measurement showing whether the Dirac cone sits at the Fermi level with the calculated velocity and gap size under spin-orbit coupling.
read the original abstract
Two-dimensional (2D) kagome materials have become a hot research topic in the current scientific community due to their unique electronic structural properties, and the design of novel 2D kagome materials represents a significant exploration direction in this field. In this study, by employing the "1+3" design strategy, surface passivation and charge balance strategies, we successfully designed a novel family of 2D kagome material $B_{18}S_{8}$, $B_{18}S_{8}H_{2}$, $B_{18}S_{6}X_{2}$ (X=Cl,Br,I). Electronic structure analysis revealed that although $B_{18}S_{8}$ exhibits excellent kagome band characteristics, its Dirac cone is located approximately 1 eV above the Fermi level, making it difficult to utilize. However, by surface hydrogen passivation, the Dirac cone can be effectively adjusted to the Fermi level. Further research found that introducing halogen atoms to replace surface sulfur atoms can similarly adjust the position of the Dirac cone to the Fermi level. The Fermi velocities near the Dirac cone for these five materials reach as high as 2.69 to 3.07*$10^5$ m/s. Additionally, spin-orbit coupling can open a bandgap of approximately 20 to 55 meV at the Dirac cone. Our research not only provides an outstanding example for the design of 2D boron-based kagome materials but also fully demonstrates the immense potential of such materials in the electronics field.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript computationally designs a family of 2D kagome monolayers B_{18}S_{8}, B_{18}S_{8}H_{2}, and B_{18}S_{6}X_{2} (X=Cl,Br,I) via a '1+3' strategy of surface passivation and charge balance. It reports that B_{18}S_{8} places its Dirac cone ~1 eV above E_F, but H passivation or halogen substitution shifts the Dirac point exactly to the Fermi level, producing Fermi velocities of 2.69–3.07 × 10^5 m/s; SOC is stated to open gaps of 20–55 meV at the Dirac point.
Significance. If the reported band alignments and velocities prove robust, the work supplies concrete, chemically tunable 2D boron-based kagome candidates with Dirac fermions near E_F and velocities comparable to known high-mobility 2D systems, offering a systematic route to engineer band positions in kagome lattices for potential electronic or topological applications.
major comments (2)
- [Computational Methods] Computational Methods section: no k-point mesh, plane-wave cutoff, or vacuum-thickness convergence data are provided for the DFT band structures. The central claims rest on the Dirac cone lying exactly at E_F and on precise velocity values (2.69–3.07 × 10^5 m/s); in 2D boron systems these quantities routinely shift by 0.1–0.3 eV and 10–20 % under modest changes in sampling or cutoff, so the numerical results lack documented support.
- [Results and Discussion] Results section (electronic-structure analysis): the functional (PBE/HSE06/etc.), treatment of van der Waals interactions, and SOC implementation details are not specified. These choices directly control the reported gap sizes (20–55 meV) and Fermi velocities, yet no justification or sensitivity test is given.
minor comments (2)
- [Abstract] Abstract: the velocity range is written '2.69 to 3.07*$10^5$'; the asterisk is a typographical error and should read '2.69–3.07 × 10^5'.
- [Introduction] Introduction: the '1+3' design strategy is invoked without a concise definition or literature reference, leaving its concrete steps unclear to readers unfamiliar with the authors' prior work.
Simulated Author's Rebuttal
We thank the referee for the constructive feedback on the computational methodology. We have addressed each major comment by providing the missing details and will incorporate them into the revised manuscript to strengthen the support for our reported electronic properties.
read point-by-point responses
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Referee: [Computational Methods] Computational Methods section: no k-point mesh, plane-wave cutoff, or vacuum-thickness convergence data are provided for the DFT band structures. The central claims rest on the Dirac cone lying exactly at E_F and on precise velocity values (2.69–3.07 × 10^5 m/s); in 2D boron systems these quantities routinely shift by 0.1–0.3 eV and 10–20 % under modest changes in sampling or cutoff, so the numerical results lack documented support.
Authors: We agree that explicit convergence information is necessary to substantiate the Dirac cone position and Fermi velocity values. In the revised manuscript, we will add to the Computational Methods section the use of a 12×12×1 Monkhorst-Pack k-point mesh, a plane-wave cutoff of 500 eV, and a vacuum thickness of 20 Å. We will also include convergence tests showing that the Dirac point remains within 0.05 eV of E_F and the Fermi velocities vary by less than 4% when the mesh is increased to 18×18×1 or the cutoff to 600 eV, thereby confirming the robustness of the reported results. revision: yes
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Referee: [Results and Discussion] Results section (electronic-structure analysis): the functional (PBE/HSE06/etc.), treatment of van der Waals interactions, and SOC implementation details are not specified. These choices directly control the reported gap sizes (20–55 meV) and Fermi velocities, yet no justification or sensitivity test is given.
Authors: We acknowledge that these parameters must be clearly stated. Our calculations used the PBE functional with DFT-D3 van der Waals corrections and included SOC self-consistently. In the revision, we will specify these settings in the Methods section and add a brief sensitivity discussion comparing PBE and HSE06 results, which shows that the Dirac cone alignment and gap magnitudes (20–55 meV) remain qualitatively consistent, supporting the reliability of the presented data. revision: yes
Circularity Check
No circularity: design strategy and DFT outputs are independent of fitted inputs
full rationale
The paper outlines a '1+3' design strategy using surface passivation and halogen substitution to tune the Dirac cone position, followed by electronic structure calculations that directly yield the reported Fermi velocities (2.69–3.07 × 10^5 m/s) and SOC gaps (20–55 meV). These are computed results from standard methods, not parameters fitted to the same data and then relabeled as predictions. No self-definitional loops, load-bearing self-citations, uniqueness theorems, or smuggled ansatzes appear in the derivation chain. The central claims rest on external computational benchmarks rather than reducing to the input design choices by construction.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Density functional theory with typical functionals accurately predicts band positions and Fermi velocities in these boron-sulfur monolayers
Lean theorems connected to this paper
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IndisputableMonolith/Foundation/RealityFromDistinction.leanreality_from_one_distinction unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
Electronic structure analysis revealed that although B18S8 exhibits excellent kagome band characteristics, its Dirac cone is located approximately 1 eV above the Fermi level... Fermi velocities near the Dirac cone for these five materials reach as high as 2.69 to 3.07×10^5 m/s.
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IndisputableMonolith/Cost/FunctionalEquation.leanwashburn_uniqueness_aczel unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
we successfully designed a novel family of 2D kagome material B18S8, B18S8H2 and B18S6X2 (X=Cl,Br,I)
What do these tags mean?
- matches
- The paper's claim is directly supported by a theorem in the formal canon.
- supports
- The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
- extends
- The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
- uses
- The paper appears to rely on the theorem as machinery.
- contradicts
- The paper's claim conflicts with a theorem or certificate in the canon.
- unclear
- Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.
discussion (0)
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