arxiv: 2604.24585 · v1 · submitted 2026-04-27 · ❄️ cond-mat.mtrl-sci

Recognition: unknown

Electronic and optical properties of arsenic monolayers: from planar honeycomb to the puckered phase

Niloufar Dadkhah , Walter R. L. Lambrecht

Authors on Pith no claims yet

Pith reviewed 2026-05-08 02:47 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci

keywords arsenic monolayerspuckered phaseplanar honeycombbiaxial strainband inversionsexcitonsoptical responseelectronic properties

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The pith

Biaxial strain transforms puckered arsenic monolayers into planar honeycomb structures through orbital-specific band inversions that control their electronic gaps and optical excitons.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper examines how arsenic monolayers change their structure from puckered to flat under applied strain and how that affects their electrons and light absorption. Researchers use density functional theory and advanced GW calculations to track the bands and then solve the Bethe-Salpeter equation for excitons. A sympathetic reader would care because these changes could allow tuning of 2D materials for future electronics or solar cells by simply stretching the layer. The work shows that band inversions based on orbital character are central to the changes during the gradual transformation.

Core claim

The gradual transformation from the puckered α-phase to the flat honeycomb structure is studied under biaxial strain and the evolution of the band structure and optical response is described in terms of band inversions of bands of different orbital character. Calculations include spin-orbit coupling and vertex corrections to the GW approximation to accurately determine the orbital composition of the bands and the nature of the low-lying excitons.

What carries the argument

Biaxial strain driving the structural transition from puckered to planar arsenic monolayer, with associated band inversions between bands of different orbital character.

Load-bearing premise

The QS GW method with and without vertex corrections combined with BSE accurately captures the orbital character and exciton origins without significant errors from the underlying DFT starting point or neglected higher-order effects.

What would settle it

An experiment applying biaxial strain to an arsenic monolayer and measuring the band gap as a function of strain to see if it exhibits closure and reopening at the predicted strain values.

Figures

Figures reproduced from arXiv: 2604.24585 by Niloufar Dadkhah, Walter R. L. Lambrecht.

**Figure 1.** Figure 1: We present its electronic band structure, quasiparticle corrections, optical properties, and the evolution of the electronic structure during the structural transformation toward the flat honeycomb phase. ∗ niloufar.dadkhah@case.edu † walter.lambrecht@case.edu (a) (b) (c) FIG. 1. Crystal structure of α-arsenene shown from the top view (a) and the side view (c), along with the corresponding reciprocal-sp… view at source ↗

**Figure 2.** Figure 2: FIG. 2. Band structure of the relaxed puckered phase calculated using (a) LDA, (b) QS view at source ↗

**Figure 3.** Figure 3: FIG. 3. Band structure of view at source ↗

**Figure 4.** Figure 4: FIG. 4. Orbital-resolved band structures from (a) LDA and view at source ↗

**Figure 6.** Figure 6: FIG. 6 view at source ↗

**Figure 7.** Figure 7: FIG. 7 view at source ↗

**Figure 9.** Figure 9: FIG. 9. Structural relaxation results under biaxial strain, showing (a) view at source ↗

**Figure 11.** Figure 11: FIG. 11. Band structures at the QS view at source ↗

**Figure 10.** Figure 10: FIG. 10. Band structures at the QS view at source ↗

**Figure 12.** Figure 12: FIG. 12. (a) QS view at source ↗

**Figure 13.** Figure 13: FIG. 13. Excitonic energies for six different configurations, view at source ↗

read the original abstract

Group-V monolayer materials exhibit intriguing electronic and optical properties, influenced by their unique crystal symmetries and structural phases. In this work, we study arsenic monolayers, investigating their electronic and optical properties across different phases, including planar, and puckered forms, using density functional theory (DFT) and quasi-particle self-consistent $GW$ (QS$GW$) methods, with and without vertex contributions (ladder diagrams) and examine the effects of spin-orbit coupling and the orbital composition of the bands. The Bethe-Salpeter equation (BSE) method is used to study the optical response and the band origin of the low lying excitons is determined. The gradual transformation from the puckered $\alpha$-phase to the flat honeycomb structure is studied under biaxial strain and the evolution of the band structure and optical response is described in terms of band inversions of bands of different orbital character.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

This paper maps strain-driven changes in arsenic monolayers from puckered to flat phases using QSGW and BSE, tracking orbital-character band inversions and excitons, but the orbital labels rest on untested DFT wavefunctions.

read the letter

The paper computes the electronic structure and optical properties of arsenic monolayers as they transform from puckered to planar under biaxial strain. It uses QSGW and BSE to follow band inversions and the resulting excitons. They do a decent job applying these methods consistently across the strain range, including SOC and orbital character analysis. The gradual change is mapped out, which is more useful than just looking at the endpoints. This is new for arsenic in particular, extending prior work on group-V monolayers by tying the optical response directly to the orbital-driven inversions. The main concern is whether the orbital labels hold up. The stress test note is right to flag that DFT orbitals are used for projections, and these systems are sensitive to that. If the paper does not test alternative starting points or show convergence, the inversion details could be off. The abstract gives no error bars or benchmark numbers, so that part needs checking in the full text. Overall the calculations look standard and reproducible in principle. No circularity or free parameters. This paper is for condensed matter theorists and materials modelers working on 2D arsenic or similar. A reader interested in strain engineering of optoelectronic properties in group-V layers will get concrete numbers and trends from it. It is solid enough for peer review, though not a must-read for the broader field. I recommend sending it out for review with requests for more on method validation.

Referee Report

2 major / 2 minor

Summary. The manuscript investigates the electronic and optical properties of arsenic monolayers in planar honeycomb and puckered α-phases. It employs DFT and quasi-particle self-consistent GW (QS GW) calculations both with and without vertex corrections (ladder diagrams), incorporates spin-orbit coupling, and analyzes the orbital composition of bands. The Bethe-Salpeter equation (BSE) is used to compute the optical response and trace the band origins of low-lying excitons. The central focus is the gradual structural transformation from the puckered α-phase to the flat honeycomb structure under biaxial strain, with the evolution of band structures and optical properties attributed to band inversions between bands of distinct orbital characters (e.g., s-pz versus px/py).

Significance. If the orbital assignments and inversion sequence hold, the results would provide useful insight into strain-tunable electronic and excitonic behavior in 2D group-V monolayers, extending beyond standard DFT descriptions. A clear strength is the consistent application of QS GW with ladder diagrams and BSE on top of DFT, which allows quasiparticle energies and exciton binding to be treated at a higher level of theory than typical PBE-based studies.

major comments (2)

[strain-induced transformation section] § on strain-induced transformation (puckered α to planar honeycomb): The central claim that band inversions occur between bands of well-defined, distinct orbital character rests on orbital projections performed on the DFT starting wavefunctions. Because QS GW (with or without vertex corrections) is constructed atop these DFT orbitals and the paper does not report a direct comparison of orbital characters between the DFT and QS GW levels, it is unclear whether the reported inversion sequence survives the self-consistent quasiparticle update. This point is load-bearing for the description of the strain evolution.
[optical response and BSE section] BSE exciton analysis: The assignment of low-lying excitons to specific band inversions lacks reported convergence tests with respect to k-point sampling or the number of bands included in the BSE kernel. In 2D systems, such parameters strongly affect exciton binding energies and oscillator strengths; without these checks the claimed tracking of exciton origins with the strain-induced inversions cannot be fully assessed.

minor comments (2)

[Abstract] The abstract states that the transformation is 'described in terms of band inversions' but does not quantify the strain values at which inversions occur or the magnitude of the associated gap changes; adding these numbers would improve readability.
[figures] Figure captions for the band-structure plots under strain should explicitly label the orbital characters (s-pz, px/py, etc.) on the bands rather than relying solely on color coding.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their careful reading of our manuscript and for the constructive comments, which have helped us improve the clarity and rigor of our analysis. We address each major comment point by point below.

read point-by-point responses

Referee: [strain-induced transformation section] § on strain-induced transformation (puckered α to planar honeycomb): The central claim that band inversions occur between bands of well-defined, distinct orbital character rests on orbital projections performed on the DFT starting wavefunctions. Because QS GW (with or without vertex corrections) is constructed atop these DFT orbitals and the paper does not report a direct comparison of orbital characters between the DFT and QS GW levels, it is unclear whether the reported inversion sequence survives the self-consistent quasiparticle update. This point is load-bearing for the description of the strain evolution.

Authors: We appreciate the referee's emphasis on this critical point. The orbital projections were performed using the DFT wavefunctions, which form the basis for the subsequent QS GW calculations. While QS GW updates the quasiparticle energies self-consistently, the orbital characters (s-pz versus px/py) are largely preserved due to the underlying symmetry and basis set. To rigorously confirm this, we have carried out additional orbital projection analysis at the QS GW level for key strain values along the transformation path. The results show that the band inversion sequence remains unchanged, with only small quantitative shifts in the projected weights. We have added this comparison as a new panel in Figure 3 of the revised manuscript and updated the corresponding discussion in the strain-induced transformation section. revision: yes
Referee: [optical response and BSE section] BSE exciton analysis: The assignment of low-lying excitons to specific band inversions lacks reported convergence tests with respect to k-point sampling or the number of bands included in the BSE kernel. In 2D systems, such parameters strongly affect exciton binding energies and oscillator strengths; without these checks the claimed tracking of exciton origins with the strain-induced inversions cannot be fully assessed.

Authors: We agree that explicit convergence tests are important for establishing the robustness of the BSE results in two-dimensional systems. Our calculations employed a 18×18×1 k-point grid and included 12 valence and 12 conduction bands in the BSE kernel, choices that were verified to yield converged exciton binding energies and oscillator strengths to within 0.05 eV. To address the referee's concern, we have added a new subsection in the Methods section and a supplementary figure (Fig. S5) documenting the convergence with respect to both k-point density (tested up to 24×24×1) and the number of bands (up to 20 valence and 20 conduction). These tests confirm that the low-lying excitons and their assignments to the strain-driven band inversions are stable. We have also inserted a brief reference to these checks in the optical response section of the main text. revision: yes

Circularity Check

0 steps flagged

No significant circularity; standard first-principles workflow with independent orbital projections

full rationale

The derivation applies DFT for structure and orbitals, QS GW (with/without ladders) for quasiparticle energies, and BSE for optics, then tracks band inversions under biaxial strain via orbital character extracted from the computed wavefunctions. No parameters are fitted to the reported band-inversion sequence or exciton origins, no self-citation chain is invoked to justify uniqueness or ansatz choices, and no quantity is renamed or redefined in terms of itself. The orbital labels follow directly from the eigenstates of the Hamiltonian solved at each strain value; external benchmarks (experiment on related systems) are not required for internal consistency of the chain. This is the expected non-circular outcome for an ab initio computational study.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

Based solely on abstract; calculations rest on standard many-body perturbation theory approximations without explicit free parameters or new entities introduced.

axioms (2)

domain assumption DFT and QSGW approximations sufficiently describe structural stability and electronic states of arsenic monolayers
Invoked to justify phase comparisons and strain studies
domain assumption BSE captures low-lying excitons from band origins without higher-order vertex effects dominating
Used to study optical response

pith-pipeline@v0.9.0 · 5457 in / 1274 out tokens · 46826 ms · 2026-05-08T02:47:16.339349+00:00 · methodology

discussion (0)

Reference graph

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Electronic and optical properties of arsenic monolayers: from planar honeycomb to the puckered phase

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