{"id":"3c1f4ba7-da8b-45b9-9ef1-b6d9e48fd470","arxiv_id":"2607.04651","paper_version":1,"verdict":"CONDITIONAL","confidence":"HIGH","novelty_score":3.5,"correctness_risk":"medium","formal_verification":"none","parameter_count":3,"one_line_summary":"First-principles calculations find ZrRuAs and HfRuP ductile topological semimetals with phonon-mediated Tc of 9.75 K and 9.03 K under strong electron–phonon coupling.","lead":"DFT calculations map the electronic, mechanical, optical, thermodynamic, and phonon-mediated superconducting properties of ZrRuAs and HfRuP. The work fills property gaps for two known topological-superconductor candidates and estimates Tc near 9–10 K.","discovery_kind":"extension","skeptic_critique":{"model":"grok-4.5","headline":"Hand-set μ*=0.10 and SOC-free EPC are the load-bearing soft spots for the Tc claim, but they are standard and do not break the paper’s internal logic.","rationale":"The Reader correctly isolates the two softest assumptions that underwrite the strongest claim (EPC-derived Tc and strong-coupling assignment). Both are standard in the field and do not render the calculation circular or formally invalid; they simply leave the quantitative Tc numbers under-constrained relative to experiment (~12 K). The topological part largely reconfirms prior work and is not load-bearing for the new property survey. No deeper inconsistency (e.g., dynamical instability, wrong stability criteria, or self-contradictory band topology) appears. Therefore the CONDITIONAL verdict already assigned by the Reader remains the appropriate one; the concrete μ*/SOC sensitivity check above is exactly the minimal addition that would convert the paper from conditional to more robust. No stronger objection is warranted.","tokens_in":25968,"tokens_out":556,"duration_ms":5026,"concrete_test":"Recompute λ, ωlog and Tc for both compounds at μ*=0.10, 0.13 and 0.15, and recompute the HfRuP phonon/EPC spectrum once with SOC on the same 3×3×3 q-mesh; if any of the three μ* values or the SOC run moves Tc outside 7–12 K or drops λ below ~0.9, the “strong-coupling conventional” headline weakens.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central superconducting claim (λ=1.18/1.30 → Tc=9.75/9.03 K via Allen–Dynes, strong-coupling phonon-mediated regime) rests on two untested modeling choices in §3.5: (i) μ* fixed at 0.10 with no material-specific estimate or scan, and (ii) phonon/EPC spectra computed without SOC, justified only by citations that the effect is “considered insignificant.” Because Tc depends exponentially on (λ−μ*(1+0.62λ)), a modest shift of μ* into the usual 0.10–0.15 window moves Tc by several kelvin and can change whether the numbers sit below or near the experimental ~12 K. For HfRuP the heavier atom makes the SOC-omission assumption least secure; if SOC softens or hardens the low-frequency Ru modes that supply ~68–78 % of λ, both λ and ωlog (and therefore the strong-coupling classification) can shift. These are real but conventional DFT caveats, not internal contradictions.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.5","summary":"This manuscript presents a broad first-principles study (Quantum ESPRESSO/CASTEP, PBE-GGA, DFPT, GIBBS2, WannierTools) of the hexagonal ZrNiAl-type compounds ZrRuAs and HfRuP. It reports optimized structures, electron-density difference maps, elastic constants and derived mechanical indices, optical spectra with a Drude term, quasi-harmonic thermodynamic quantities, bulk bands with and without SOC, Fermi surfaces, surface spectral functions, phonon dispersions, Eliashberg α²F(ω), and Allen–Dynes Tc estimates. The central claims are that both materials are mechanically stable and ductile, exhibit topological semimetallic character consistent with prior classification (ZrRuAs as a topological crystalline insulator; HfRuP as a type-II Weyl semimetal), and are conventional phonon-mediated superconductors with λ = 1.18 and 1.30 and Tc ≈ 9.75 K and 9.03 K (μ* = 0.10), driven mainly by low-frequency out-of-plane Ru modes.","tokens_in":26213,"tokens_out":1520,"duration_ms":19796,"significance":"ZrRuAs and HfRuP are established experimental superconductors (Tc ~12–13 K) that have been proposed as topological materials; a single study that ties elastic, optical, thermodynamic, topological, and EPC properties together is therefore of genuine interest to the topological-superconductor and intermetallic communities. Strengths include Born-stable elastic constants, dynamically stable phonons, explicit mode-resolved PhDOS and EPC weighting showing that phonons below ~100 cm⁻¹ supply ~68–78% of λ, and surface spectral functions that qualitatively track the prior topological assignments of Qian et al. If the superconducting and topological conclusions hold under tighter checks, the work usefully closes documented gaps on machinability, optical response, and thermophysical behavior for these Ru-based ternary pnictides.","major_comments":[{"comment":"§3.5, Eq. (14) and Table 4: Tc is obtained with a fixed Coulomb pseudopotential μ* = 0.10 and no material-specific estimate or sensitivity scan. Because Tc depends exponentially on [λ − μ*(1 + 0.62λ)], shifting μ* over the conventional 0.10–0.15 window changes Tc by several kelvin and can move the results relative to the experimental ~12–13 K values. A short μ* scan (or a Morel–Anderson-style estimate) is needed to show that the strong-coupling classification and the reported Tc ordering (ZrRuAs > HfRuP) are robust.","section":null},{"comment":"§2 and §3.5: Phonon and EPC spectra are computed without SOC, justified only by the statement that the effect is “considered insignificant” and by citations to other systems. For HfRuP the heavy Hf atom makes this assumption least secure; the same low-frequency Ru modes that dominate λ (~68% of the total) could soften or harden under SOC, shifting both λ and ωlog. At minimum the manuscript should either (i) report a SOC phonon check at selected q-points for HfRuP or (ii) quantify the expected error and temper the strong-coupling claim accordingly.","section":null},{"comment":"§3.5 and Conclusions vs. experimental literature cited in the Introduction: Calculated Tc values (9.75 K / 9.03 K) systematically underestimate the reported experimental Tc (~12 K for ZrRuAs; ~12.7 K for HfRuP). The text asserts consistency with prior experimental reports without discussing the discrepancy, the role of μ*, mesh convergence of α²F(ω), or possible pressure/stoichiometry effects. A quantitative comparison and an explicit discussion of why theory sits ~3 K below experiment are load-bearing for the superconducting claim.","section":null},{"comment":"§3.2.1 (band structure / surface states) and Abstract/Conclusions: Topological assignments (TCI for ZrRuAs; type-II Weyl for HfRuP) rest largely on qualitative band crossings, SOC gap openings, and surface spectral intensity near K, together with citation of Ref. [58]. The manuscript does not report computed topological invariants (mirror Chern numbers, Weyl-node chirality/locations, or Z2) for the present DFT setup. Either compute the relevant invariants with the same Wannier model used for Fig. 5, or clearly reframe the topological section as a consistency check with prior theory rather than an independent classification.","section":null}],"minor_comments":[{"comment":"Abstract vs. §3.5/Conclusions: coupling strength is called “strong” in places and “medium-coupling” in the abstract body; with λ = 1.18–1.30 the language should be unified (intermediate-to-strong is conventional).","section":null},{"comment":"§3.3.2 Reflectivity paragraph: compound names are swapped (“HfRuAs”, “ZrRuP”); correct to ZrRuAs and HfRuP.","section":null},{"comment":"Figure 8 panel labels in the text (e.g. refractive index referred to as 8(e), absorption as 8(c)) do not match the figure caption ordering; renumber or re-letter for consistency.","section":null},{"comment":"Table 1: experimental lattice parameters are listed under a blank “Functionals” row with Ref. [58]; clarify whether those are experimental or previously calculated values.","section":null},{"comment":"Optical Drude parameters (plasma energy 10 eV vs 5 eV, damping 0.05 eV) are stated without justification or sensitivity; a brief note on how they were chosen would help reproducibility.","section":null},{"comment":"§3.2 Mechanical section is numbered “3.2” and electronic band structure is also under “3.2.1”; renumber subsections for a clean hierarchy.","section":null},{"comment":"Several typographical issues: “machinability”/“machinability index” spelling varies; “Pugh’s ratio k (G/B)” in Table 3 header is inverted relative to the G/B values discussed as ductile when G/B < 0.57; “Hf RuP” spacing; “zero photon energy” phrasing.","section":null},{"comment":"Conclusions speculate that moderate pressure will substantially change Tc without presenting pressure-dependent EPC; either add a short calculation or mark the statement as a suggestion for future work.","section":null}],"recommendation":"major_revision","confidential_remarks":"The paper is a solid multi-property DFT survey of known superconductors rather than a discovery of new topology or a decisive resolution of the pairing mechanism. Scope fits a materials-physics or computational-condensed-matter journal; for a high-impact venue the missing μ*/SOC checks and the lack of new topological invariants would be more serious. Citation of the key prior topology paper [58] is appropriate and not concealed. No integrity concerns noted."},"author_rebuttal":null,"desk_editor":{"model":"grok-4.5","letter":"This is a workmanlike first-principles survey of ZrRuAs and HfRuP. What is actually new is the elastic constants (Born-stable, ductile by Pugh/Poisson/Cauchy, soft and machinable), optical spectra with Drude terms, quasi-harmonic thermodynamics via GIBBS2, and DFPT phonon-resolved EPC that yields λ = 1.18/1.30 and Allen–Dynes Tc ≈ 9.75/9.03 K. Those numbers sit a few kelvin below the experimental ~12–13 K but place both compounds in the conventional strong/intermediate-coupling phonon-mediated regime, with low-frequency Ru out-of-plane modes carrying most of λ. Phonons are stable, Fermi surfaces show mixed electron/hole sheets, and surface spectral functions are consistent with the earlier Qian et al. classification (Weyl for HfRuP, topological crystalline insulator for ZrRuAs).\n\nThe paper does the standard things carefully: QE/CASTEP PBE, stress–strain elastic constants, DFPT + Eliashberg, mode-projected PhDOS. Citation pattern is honest about Shirotani and Qian; it does not pretend the topology or the existence of superconductivity is new. Soft spots are real but conventional and proportionate. μ* is fixed at 0.10 with no scan; Tc is exponentially sensitive, so a shift into the usual 0.10–0.15 window moves the numbers by several kelvin. SOC is omitted from the phonon/EPC runs for the heavier Hf compound on the strength of generic citations rather than a check. Drude plasma energies are hand-set. None of this breaks the internal logic or invents entities; it is the usual DFT materials-science package.\n\nWho it is for: people already working on TT′X topological candidates or needing processing-relevant numbers (ductility, reflectivity, thermal expansion). It will not change practice outside that niche. I would send it to peer review; a serious referee can ask for a μ* sensitivity plot, a clearer new-vs-prior topology paragraph, and data release. Worth a look if you need the property tables; not a must-read for the broader topological-SC community.","headline":"Solid multi-property DFT map of two known ~12 K TT′X superconductors; new elastic/optical/thermo/EPC numbers are useful, topology and Tc mostly reconfirm prior work with standard caveats.","tokens_in":26909,"tokens_out":581,"would_cite":true,"duration_ms":5766,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"grok-4.5","headline":"ZrRuAs and HfRuP are ductile topological semimetals with strong-coupling phonon-mediated superconductivity near 9–10 K.","keywords":["Topological quantum materials","Topological superconductor","Ru-based ternary pnictides","Thermophysical properties","Optoelectronic properties","Electron-phonon coupling","ZrRuAs","HfRuP"],"falsifier":"A measured superconducting transition temperature for single-phase ZrRuAs or HfRuP that lies well outside the 9–10 K window predicted by Allen–Dynes with λ ≈ 1.2 and μ* = 0.10, or a phonon calculation with spin–orbit coupling that substantially changes λ or the soft-mode weight.","tokens_in":26827,"feed_emoji":"❄️","tokens_out":938,"duration_ms":19951,"temperature":0.7,"pith_summary":"This paper sets out a full first-principles map of two Ru-based ternary pnictides, ZrRuAs and HfRuP, that already look like topological superconductors from earlier work. It shows that both compounds are mechanically stable and ductile, with mixed metallic–covalent bonding, metallic optical reflectivity, and thermodynamic stability under pressure and temperature. Electron–phonon coupling calculations place them in the strong-coupling conventional regime, with predicted transition temperatures of 9.75 K and 9.03 K. The same electronic-structure analysis supports topological semimetallic character—consistent with a topological crystalline insulator picture for ZrRuAs and a type-II Weyl picture for HfRuP—while filling in the elastic, optical, and thermophysical properties that had not been studied in detail. A sympathetic reader cares because these materials combine processable ductility with topology and phonon-mediated superconductivity in a single family of intermetallics.","feed_headline":"Two Ru pnictides superconduct near 10 K with topology","feed_subtitle":"DFT finds strong electron–phonon coupling and ductile, processable topological semimetals","key_machinery":"Electron–phonon coupling strength λ(ω) and the Eliashberg spectral function α²F(ω) from density-functional perturbation theory, inserted into the Allen–Dynes modified McMillan formula with μ* = 0.10 to obtain Tc.","core_discovery":"Density-functional calculations of structure, bands, surface spectra, elasticity, optics, thermodynamics, phonons, and electron–phonon coupling establish that ZrRuAs and HfRuP are dynamically and mechanically stable topological semimetals that are ductile and machinable, and that they are strong-coupling conventional superconductors with Tc ≈ 9.75 K (ZrRuAs) and 9.03 K (HfRuP) driven mainly by soft low-frequency Ru out-of-plane modes.","pith_inferences":["Because experimental Tc values reported for the hexagonal family sit near 12–13 K, the calculated 9–10 K values imply that either μ* is slightly lower than 0.10 or anharmonic/pressure effects missing from the quasi-harmonic treatment raise the effective coupling.","The soft ductile response suggests moderate hydrostatic pressure could be used as a continuous knob on both band topology and Tc without fracturing the lattice.","If surface Majorana modes are later sought, HfRuP’s Weyl classification makes it the more natural platform of the pair for engineered superconducting interfaces."],"forward_implications":["Both compounds should remain ductile and machinable enough for wire or magnet applications typical of intermetallic superconductors.","Low-frequency Ru vibrations dominate pairing, so pressure or doping that hardens those modes should suppress Tc while lattice expansion should raise it.","Surface-sensitive probes on HfRuP should see robust gapless states near the Fermi level consistent with type-II Weyl points; ZrRuAs should show partially gapped crystalline-surface states.","Strong metallic reflectivity and ultraviolet absorption make the materials candidates for reflective coatings or UV optoelectronic use in the calculated energy windows."],"fun_headline_variants":["ZrRuAs and HfRuP: topological semimetals superconduct near 10 K","Phonon-driven Tc near 10 K in topological Ru pnictides","Ductile topological semimetals ZrRuAs HfRuP with Tc ~9–10 K","Strong-coupling superconductivity in Ru-based topological pnictides","Topological bands plus 9 K superconductivity in ZrRuAs and HfRuP"],"cache_read_input_tokens":16512,"weakest_assumption_plain":"The Coulomb repulsion parameter is fixed by hand at 0.10 and spin–orbit coupling is dropped from the phonon and coupling calculations without a material-specific check.","fun_headline_variants_meta":{"raw":{"variants":["ZrRuAs and HfRuP: topological semimetals superconduct near 10 K","Phonon-driven Tc near 10 K in topological Ru pnictides","Ductile topological semimetals ZrRuAs HfRuP with Tc ~9–10 K","Strong-coupling superconductivity in Ru-based topological pnictides","Topological bands plus 9 K superconductivity in ZrRuAs and HfRuP"]},"model":"grok-4.5","effort":"low","cost_usd":0.003674,"raw_usage":{"total_tokens":1143,"prompt_tokens":748,"num_sources_used":0,"completion_tokens":110,"cost_in_usd_ticks":36740000,"prompt_tokens_details":{"text_tokens":748,"audio_tokens":0,"image_tokens":0,"cached_tokens":128},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":285,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":748,"tokens_out":110,"duration_ms":2712,"temperature":1.0,"reasoning_tokens":285,"cache_read_input_tokens":128,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-07-11T15:45:27.162276+00:00","model_set":{"reader":"grok-4.5"},"falsifier":"A measured superconducting transition temperature for single-phase ZrRuAs or HfRuP that lies well outside the 9–10 K window predicted by Allen–Dynes with λ ≈ 1.2 and μ* = 0.10, or a phonon calculation with spin–orbit coupling that substantially changes λ or the soft-mode weight.","supporting_citations":[],"review_version":1}