{"id":"b36a9f7f-83cf-4085-8892-23aadfe19182","arxiv_id":"2608.09020","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":1,"one_line_summary":"K-doped cubic SrAsO3 is predicted to be a phonon-mediated superconductor with HSE06-corrected Tc of about 44.3 K at 60% potassium doping.","lead":"This paper predicts that a never-made oxide, K-doped SrAsO3, could be a superconductor with a transition temperature around 44 K. It uses computer simulations of electrons, atomic vibrations, and their coupling to make the prediction.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"VCA-stabilized cubic phase at x=0.6 may not survive explicit Sr/K disorder; supercell phonon test needed.","rationale":"The reader's weakest assumption—that VCA may not capture real K-substitution effects—is the same concern I would rank first. The entire doping series (Fig. S1, Fig. 5) is computed on VCA cells, and the HSE06 stability check at x=0.6 tests only one of the parent instabilities (Sec. 3.4). Because the parent compound has instabilities at Γ, M, and R (Sec. 3.1), and because K/Sr differ in radius and valence, VCA averaging could in principle suppress the very soft modes that would destabilize the cubic phase in a real crystal. This is more load-bearing than the REPME mode-selection issue: an overestimated HSE06 enhancement factor would lower Tc but still leave a superconducting cubic phase; a VCA-spurious stabilization would remove the phase entirely. I therefore recommend the reader's CONDITIONAL verdict be kept. The concrete supercell phonon test would settle the concern; until it is done, the predicted Tc of 44.3 K should be treated as a synthesis target, not a robust quantitative claim. Secondary concerns—no input files, REPME applied as a single average factor to the total λ, and the ad hoc 59% renormalization at x=0.9—do not change this verdict.","tokens_in":10447,"tokens_out":8152,"duration_ms":72794,"concrete_test":"Construct a 25-atom (5-formula-unit) supercell of Sr0.4K0.6AsO3 with an ordered 2 Sr/3 K arrangement on the A sites (e.g., alternating along one axis). Relax the cell shape and internal coordinates within LDA (or PBE), then compute the phonon spectrum with the finite-displacement method at the relaxed geometry. If the supercell develops imaginary modes (octahedral rotations, breathing, or A-site off-centering) or relaxes to a non-cubic structure, the VCA-based cubic phase of Fig. S1 is not representative of the real doped material. Repeat for at least one alternative Sr/K ordering to check sensitivity.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The headline result—Sr0.4K0.6AsO3 as a dynamically stable cubic superconductor with HSE06-corrected λ=1.41 and Tc=44.3 K (Sec. 3.4, Table 1)—rests on the virtual crystal approximation for every doped structure (Sec. II). VCA replaces the mixed Sr/K site with an average atom, eliminating mass disorder and local strain. For the claim to hold, the real K-substituted crystal must be a cubic metal with no octahedral rotations or local relaxations. The only beyond-LDA stability check reported is a single total-energy comparison at x=0.5 vs x=0.6 for one M-point O-stretching distortion (Sec. 3.4); it does not test R-point tilts, A-site off-centering, or combinations of the parent instabilities (Sec. 3.1), and it is performed on a VCA cell, not on a cell with explicit K/Sr. Because the undoped phase is unstable at Γ, M, and R, VCA averaging could artificially suppress the soft modes that real disorder would preserve. If an explicit supercell relaxes to a tilted or distorted ground state, the metallic cubic phase and its strong EPC would not exist at x=0.6, invalidating the central prediction.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The paper uses density functional theory (LDA and HSE06) and density functional perturbation theory (DFPT) to predict that K-doped SrAsO3 and BaAsO3 perovskites become dynamically stable cubic metals at sufficiently high K doping, with strong electron-phonon coupling giving conventional phonon-mediated superconductivity. The headline result is that Sr0.4K0.6AsO3 has an HSE06-corrected electron-phonon coupling constant lambda = 1.41 and a predicted Tc of about 44.3 K, which would make it the highest-Tc member of the BaBiO3-like perovskite family. The central prediction rests on virtual crystal approximation (VCA) models for all doped structures, a REPME-based renormalization applied to selected phonon modes, and a single Coulomb pseudopotential mu* = 0.1.","tokens_in":10645,"tokens_out":5809,"duration_ms":52328,"significance":"If the prediction holds, it would extend the BaBiO3 family to arsenic-based perovskites and would represent a remarkably high Tc for a conventional phonon-mediated oxide superconductor, with Tc exceeding the well-known Ba0.6K0.4BiO3 value of about 30 K. The paper is systematic, covers a doping series for two compounds, and clearly describes the HSE06-based renormalization scheme, which is benchmarked in the authors' earlier work (Ref. [7]). The explicit discussion of the x = 0.9 exclusion criterion in the Supplementary Material is also a strength, since it acknowledges one of the procedure's limitations. The main weaknesses are the exclusive reliance on VCA for disorder modeling and the extrapolation of selected-mode REPMEs to the total electron-phonon coupling, both of which directly affect the central Tc claim.","major_comments":[{"comment":"All K-doped structures are modeled entirely within the virtual crystal approximation, and the phonon stability and electron-phonon coupling results in Fig. S1 and Fig. 5 are computed on VCA cells. No explicit supercell with a real Sr/K arrangement is tested. If actual K substitution produces local relaxations, K clustering, or octahedral tilts, the predicted dynamical stabilization at x >= 0.5 and the associated lambda may not survive. The HSE06 stability check in Section 3.4 also uses VCA cells and tests only one M-point distortion, leaving R-point tilts and combined instabilities untested. A supercell calculation with explicit K/Sr substitution (even for a single ordered arrangement at x = 0.6) is needed to support the central prediction.","section":"Section II and Section 3.3"},{"comment":"The REPME renormalization is applied to only a small number of selected modes (two modes for x = 0.6), and the resulting enhancement factors are then used to scale the total LDA lambda. The paper does not demonstrate that these modes are representative of the total electron-phonon coupling or that the enhancement factor is uniform across the Brillouin zone. For x = 0.6, lambda rises from 0.67 (LDA) to 1.41 (HSE06), a factor of 2.1, so the headline Tc of 44.3 K depends sensitively on this extrapolation. A sensitivity analysis, such as comparing the weighted average of the enhancement factors against the full lambdaqv distribution, would establish the robustness of the corrected lambda.","section":"Section 3.4 and Table 1"},{"comment":"There is an internal inconsistency in the stability criterion. Section 3.2 states that imaginary phonon branches disappear completely for x >= 0.5, while Section 3.4 reports that at x = 0.5 the oxygen-stretching distorted supercell is lower in total energy than the cubic supercell, indicating the cubic phase is still unstable at that doping. This discrepancy obscures the actual stabilization boundary and affects whether x = 0.5 should be included in the EPC and Tc analysis in Table 1. The authors should reconcile the DFPT-LDA phonon criterion with the HSE06 total-energy criterion, or explicitly state which criterion is used for each claim.","section":"Section 3.2 vs Section 3.4"},{"comment":"For x = 0.9, approximately 41% of the total electron-phonon coupling is excluded from the HSE-based renormalization because a valence band crosses the Fermi level in LDA but lies below it in HSE06. This is an ad hoc, data-driven exclusion: the same reasoning could in principle apply to other doping levels, since Fig. 3 shows systematic band shifts between LDA and HSE06. The paper should either provide a systematic criterion for such exclusions or remove the x = 0.9 HSE entry from Table 1, or clearly flag it as less reliable than the other concentrations.","section":"Table 1 footnote and Supplementary Material"}],"minor_comments":[{"comment":"The phrase \"organized as following\" should read \"organized as follows,\" and the grammar of the sentence \"The rest of the paper is organized as following\" needs correction.","section":"Section I and II"},{"comment":"The \"band-broadening factor\" in Tables S1 is not precisely defined; please state that it is the ratio of the HSE06 bandwidth to the LDA bandwidth, or give the formula used.","section":"Section 3.2"},{"comment":"The column header showing the REPME enhancement factor contains garbled characters (ମନ ଢୁହ୹ନ୹ ଢୁହ୹ନ୹ଢୁହନମ), and the x = 0.5 HSE columns are empty; the paper should state explicitly that no HSE correction was applied at x = 0.5 because the phase is unstable by the HSE06 criterion.","section":"Table 1"},{"comment":"The data availability statement says the data are not publicly available; for a computational prediction paper, depositing input files such as structures, pseudopotentials, and reproducible workflows would greatly strengthen the verifiability of the results.","section":"Data Availability"},{"comment":"Reference [22] is incompletely formatted: it should read D. R. Hamann, Phys. Rev. B 88, 085117 (2013), rather than the garbled author list that currently appears.","section":"References"},{"comment":"The paper states that the REPME approach follows Ref. [7], which is self-cited; it would be helpful to state briefly what is new in the present implementation and how the method is applied to modes (e.g., oxygen-rotational modes at M and R) that were not explicitly treated in Ref. [7].","section":"Section 3.4"},{"comment":"The phrase \"BaBiO3-like superconducting perovskites\" is used for the whole family; consider defining this term more precisely in the introduction, because the As-based compounds are isovalent but not isostructural to BaBiO3 in the undoped state.","section":"Abstract and Section 1"}],"recommendation":"major_revision","confidential_remarks":"The manuscript is well within the scope of cond-mat.supr-con and makes a clear, falsifiable prediction with an interesting physical message. The main technical concern is the exclusive use of VCA for the doped structures; this is a standard approximation in the field, but for a prediction of a specific doping level and a large HSE correction, an explicit disorder test would considerably increase confidence. The REPME extrapolation and the x = 0.9 exclusion also warrant more systematic justification. The authors appear to have the expertise and tools to address these points with additional supercell and sensitivity calculations, so I do not recommend rejection, but the current manuscript needs revision before acceptance."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Bottom line: this is a plausible and clearly presented computational prediction of a new family, but the headline number 44.3 K is exactly as strong as the VCA plus selected-mode renormalization it sits on. Treat it as a motivated synthesis target, not a quantitative result.\n\nWhat is actually new: nobody has calculated or measured superconductivity in SrAsO3/BaAsO3. Extending the bismuthate/stibnate family to arsenic is a genuine prediction. The parent instabilities are characterized carefully, the doping stabilization trend is physically sensible, and the HSE06-REPME correction follows a method the group already validated on (Ba,K)SbO3. The warning that nonlocal exchange broadens bands and increases lambda is well motivated. The paper is easy to read and the DFPT part is reproducible in principle.\n\nThe soft spots, in order of importance. First and largest: all doped structures are virtual crystals. VCA averages away Sr/K mass and strain disorder, and the parent has instabilities at Gamma, M, and R. The only HSE stability check is one M-point breathing distortion at x=0.5 vs 0.6 on a VCA cell. That does not rule out R-point tilts, A-site off-centering, or explicit K/Sr ordering effects. A supercell test with explicit K is the missing evidence. Second: the REPME correction is applied only to selected modes. For x=0.9, 41% of the LDA lambda is thrown away because the relevant valence band sits below E_F in HSE; the justification is coherent but the ad hoc nature of the rule is visible. Third: mu* is fixed at 0.1 and no input/data files are released, so the exact Tc numbers are soft. None of this makes the qualitative story wrong. The mechanism claim—K doping suppresses the breathing-type instability and stabilizes a metal with strong EPC—is credible and consistent with the bismuthate analog.\n\nWho this is for: anyone tracking conventional superconductors in simple oxides/perovskites, or using VCA for doped perovskites. It deserves serious peer review. The right referee report will ask for an explicit supercell calculation, but the paper has enough new content and internal consistency to warrant that step.","headline":"A credible new-family prediction whose 44.3 K headline rests on VCA and selective renormalization; worth serious review but the number should be treated as a target, not a result.","tokens_in":11272,"tokens_out":1518,"would_cite":true,"duration_ms":14884,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"The paper predicts that potassium-doped SrAsO3, a previously unexplored perovskite, becomes dynamically stable once roughly 60% of the strontium is replaced, and superconducts at about 44.3 K through strong phonon-mediated coupling.","keywords":["superconductivity","SrAsO3","perovskite","electron-phonon coupling","K doping","virtual crystal approximation","hybrid functional","phonon-mediated superconductivity"],"falsifier":"Synthesize $\\mathrm{Sr_{0.4}K_{0.6}AsO_3}$ and measure its resistivity: a superconducting transition well below 44 K, or a nonmetallic distorted ground state, would disprove the central prediction. A cheaper first test is a phonon calculation with explicit potassium positions in a supercell instead of the virtual crystal approximation; if imaginary modes persist at $x=0.6$, the predicted cubic phase is not dynamically stable.","tokens_in":10190,"feed_emoji":"⚛️","tokens_out":17570,"duration_ms":145305,"temperature":0.7,"pith_summary":"$\\mathrm{SrAsO_3}$ is a perovskite that has not yet been reported in the crystal-structure databases, and the paper predicts that in its ideal cubic form it is dynamically unstable, with soft-phonon modes at $\\Gamma$, $M$, and $R$ that resemble the charge-density-wave distortions of $\\mathrm{BaBiO_3}$. Substituting potassium for strontium progressively hardens these modes, and once roughly 60% of the strontium is replaced the cubic phase becomes dynamically stable and metallic. The stabilized material is then predicted to be a conventional phonon-mediated superconductor with strong coupling. When nonlocal exchange is included through a hybrid-functional renormalization, the electron-phonon coupling constant rises to $\\lambda = 1.41$ in $\\mathrm{Sr_{0.4}K_{0.6}AsO_3}$ and the transition temperature is about 44.3 K. If this holds, K-doped $\\mathrm{SrAsO_3}$ would be the highest-$T_c$ member of the $\\mathrm{BaBiO_3}$-like perovskite family, above the roughly 30 K of $\\mathrm{Ba_{0.6}K_{0.4}BiO_3}$.","feed_headline":"Predicted: K-doped SrAsO3 superconducts at 44.3 K","feed_subtitle":"If the theory is right, it beats the bismuthate family's 30 K record and opens a new arsenic-based branch.","key_machinery":"The load-bearing machinery is a two-step electron-phonon calculation. In the first step, density-functional perturbation theory in the LDA gives the phonon dispersions, the phonon spectral function $\\alpha^2F(\\omega)$, and mode-resolved coupling constants $\\lambda_{\\mathbf{q}\\nu}$ for the virtual-crystal doped structures. In the second step, selected strongly coupled oxygen modes are renormalized: frozen-phonon supercell calculations in both LDA and a screened hybrid functional give the ratio of squared electron-phonon matrix elements, and these enhancement factors multiply the corresponding $\\lambda_{\\mathbf{q}\\nu}$ contributions. The hybrid functional broadens the bands near the Fermi level by about 35-50% and produces enhancement factors near 2 for the $X$-point oxygen-oscillating mode, which is the main source of the jump from $\\lambda=0.67$ to $\\lambda=1.41$ at $x=0.6$. What the doping does is to tune the soft-phonon instabilities of the parent compound—a polar mode at $\\Gamma$, As-O stretching at $M$, and breathing at $R$—into the hard, strongly coupled modes of the metal.","core_discovery":"The central claim is that the arsenic-based perovskite $\\mathrm{SrAsO_3}$ is a new member of the $\\mathrm{BaBiO_3}$-like family and that potassium doping turns it into a strong-coupling phonon-mediated superconductor. On the paper's own numbers, the undoped cubic phase is dynamically unstable; the imaginary phonon branches disappear for $x \\geq 0.5$ within the LDA and for $x \\geq 0.6$ once the M-point oxygen-stretching distortion is checked with the hybrid functional. The stabilized $\\mathrm{Sr_{1-x}K_xAsO_3}$ compounds are metallic, and the strongest electron-phonon coupling comes from oxygen vibrations: the oxygen-oscillating mode at $X$ and the oxygen-stretching mode at $M$ at low doping, with oxygen-rotational modes contributing at high doping. At $x=0.6$, the DFPT-LDA value $\\lambda=0.67$ is renormalized by hybrid-functional enhancement factors to $\\lambda=1.41$, giving a predicted $T_c$ near 44.3 K with $\\mu^*=0.1$. The paper also predicts a sister compound, $\\mathrm{BaAsO_3}$, which becomes dynamically stable only at $x\\ge0.7$ and has a lower $T_c$ near 12 K.","pith_inferences":["Beyond the paper, the same doping logic could be tested in other group-15 perovskite parents, for example the phosphorus analogue, since the argument turns on pnictogen chemistry rather than on bismuth specifically.","The virtual crystal approximation is the obvious weak point to probe: explicit supercells with ordered potassium ions and relaxed octahedral rotations would show whether the x = 0.6 cubic phase survives real disorder.","A full electron-phonon calculation beyond the selected-mode renormalization, treating nonlocal exchange self-consistently, would check whether the omitted phonon branches change lambda and therefore move the 44.3 K estimate."],"forward_implications":["A synthesized Sr0.4K0.6AsO3 sample should show a bulk superconducting transition near 44 K, provided the virtual crystal approximation survives real disorder.","The predicted exothermic synthesis route SrAs2O6 + Sr -> 2SrAsO3 (about 1.69 eV per formula unit) identifies a concrete experimental path to the parent compound.","The doping dependence forms a dome: the highest Tc occurs near x = 0.6-0.7, not at maximal doping, because low-frequency oxygen-rotation modes begin to dominate at high x.","Nonlocal exchange is not a small correction here: at x = 0.6 the LDA-only estimate is 15.3 K while the hybrid-corrected value is 44.3 K, so the two predictions are directly distinguishable by experiment."],"supporting_citations":[{"why":"Defines the Ba0.6K0.4BiO3 benchmark with Tc near 30 K that the paper's 44.3 K prediction is meant to surpass.","marker":"[4]"},{"why":"Supplies the correlation-enhancement method (REPME renormalization) used to turn LDA electron-phonon coupling into hybrid-functional-corrected lambda and Tc.","marker":"[7]"},{"why":"Provides independent evidence that nonlocal correlation enhances electron-phonon coupling in Ba1-xKxBiO3, motivating the correction applied here.","marker":"[8]"},{"why":"Reports superconductivity near 15 K in (Ba,K)SbO3, the antimony analogue whose success motivates the arsenic-based extension.","marker":"[14]"},{"why":"Establishes through earlier calculations that nonlocal electronic correlation is crucial for strong electron-phonon coupling in (Ba,K)SbO3, the computational precedent for this work.","marker":"[15]"},{"why":"Supplies the virtual crystal approximation used to construct every K-doped structure in the doping series.","marker":"[17]"},{"why":"Shows that A-site potassium doping produces superconductivity in another bismuth-oxide perovskite family, Sr1-xKxBiO3, supporting the doping strategy.","marker":"[5]"}],"fun_headline_variants":["K-doped SrAsO3 predicted to superconduct at 44 K","Arsenic-based perovskite hits 44 K in hybrid-functional prediction","Strong electron-phonon coupling drives 44 K superconductivity in SrAsO3","BaBiO3-like: K-doped SrAsO3 predicted as 44 K superconductor"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The prediction rests on treating the randomly substituted strontium and potassium sites as one average atom in the virtual crystal approximation; if real potassium atoms instead produce local distortions, clustering, or octahedral rotations, the phonon stabilization and the large electron-phonon coupling could change substantially.","fun_headline_variants_meta":{"raw":{"variants":["K-doped SrAsO3 predicted to superconduct at 44 K","Arsenic-based perovskite hits 44 K in hybrid-functional prediction","Strong electron-phonon coupling drives 44 K superconductivity in SrAsO3","BaBiO3-like: K-doped SrAsO3 predicted as 44 K superconductor"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000812,"raw_usage":{"total_tokens":3604,"prompt_tokens":1030,"completion_tokens":2574,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":646,"completion_tokens_details":{"reasoning_tokens":2488}},"tokens_in":646,"tokens_out":2574,"duration_ms":17949,"temperature":1.0,"reasoning_tokens":2488,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-14T04:17:50.038579+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Synthesize $\\mathrm{Sr_{0.4}K_{0.6}AsO_3}$ and measure its resistivity: a superconducting transition well below 44 K, or a nonmetallic distorted ground state, would disprove the central prediction. A cheaper first test is a phonon calculation with explicit potassium positions in a supercell instead of the virtual crystal approximation; if imaginary modes persist at $x=0.6$, the predicted cubic phase is not dynamically stable.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Defines the Ba0.6K0.4BiO3 benchmark with Tc near 30 K that the paper's 44.3 K prediction is meant to surpass."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Supplies the correlation-enhancement method (REPME renormalization) used to turn LDA electron-phonon coupling into hybrid-functional-corrected lambda and Tc."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Provides independent evidence that nonlocal correlation enhances electron-phonon coupling in Ba1-xKxBiO3, motivating the correction applied here."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Reports superconductivity near 15 K in (Ba,K)SbO3, the antimony analogue whose success motivates the arsenic-based extension."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Establishes through earlier calculations that nonlocal electronic correlation is crucial for strong electron-phonon coupling in (Ba,K)SbO3, the computational precedent for this work."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Supplies the virtual crystal approximation used to construct every K-doped structure in the doping series."},{"cited_title":"Kazakov, C","cited_arxiv_id":null,"evidence_quote":"Shows that A-site potassium doping produces superconductivity in another bismuth-oxide perovskite family, Sr1-xKxBiO3, supporting the doping strategy."}],"review_version":1}