{"id":"ccf32145-ff4a-4cfc-848e-72cb1ecaa8e4","arxiv_id":"2608.04789","paper_version":2,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":2,"one_line_summary":"A first-principles screening identifies HfPd2Al, TiRuSb, and ZrNi2Ga as predicted ductile superconductors with transition temperatures between 6.8 and 12.9 K.","lead":"This paper screens 250 known superconducting compounds by computer simulation to find those that are both superconducting and mechanically ductile, and proposes HfPd2Al, TiRuSb, and ZrNi2Ga as the strongest candidates. It maps mechanical properties across a wide database and offers a new composite score to rank ductile superconductors for practical applications.","discovery_kind":"new_application","skeptic_critique":{"model":"deepseek-v4-flash","headline":"The ductility claim rests on an uncalibrated Rice-ratio threshold; the three candidates' rRice values (0.44-0.55) exceed those the paper itself reports for ductile BCC metals (0.16-0.33), so the central conclusion is not yet supported.","rationale":"The paper's computational execution is careful: it validates Born-expansion elastic constants against finite-displacement results, documents q-point convergence, checks the linear-elastic strain range, and benchmarks GSFE on elemental metals. The proposed new materials are new and the screening workflow is useful. However, the central qualitative claim is the word ductile applied to HfPd2Al, TiRuSb, and ZrNi2Ga. The only microscopic evidence for this is rRice, and no cutoff or experimental calibration for that quantity is provided. The concern is not that Rice's ratio is outside current consensus; rather, it is internally suggestive of a brittleness problem: the claimed ductile compounds have rRice values higher than every ductile BCC metal benchmarked in the same paper. That fact at minimum demands an explicit threshold and a calibration check. Therefore the reader's CONDITIONAL verdict is appropriate, and this stress-test does not require moving it. Agreement with the reader is full: the weakest assumption is the same uncalibrated Rice-ratio criterion.","tokens_in":22236,"tokens_out":4427,"duration_ms":42096,"concrete_test":"Use the identical aiida-mechanical workflow, including the same (1-10) plane, same constrained out-of-plane relaxation, and same k-point/vacuum parameters, to compute rRice for a validation set of at least three experimentally ductile and three experimentally brittle intermetallics (ideally in or near the C1b/L21 Heusler families; if unavailable, cubic B2/L12 intermetallics). Plot the validation rRice values and the three candidates; if no threshold separates the known ductile from known brittle references, or if the candidates fall on the brittle side of the separation, the ductility classification fails. As a minimal analytic check, compare HfPd2Al, TiRuSb, ZrNi2Ga (0.44, 0.47, 0.55) against the paper's own Table 3 BCC metals (0.16-0.33) and report whether any Rice-Thomson literature threshold places all three on the ductile side.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim - that HfPd2Al, TiRuSb, and ZrNi2Ga are ductile superconductors - depends entirely on classifying them by Rice's ratio, rRice = gammaUSFE/gammasurface (Eq. 22). The paper never states the threshold value of rRice that separates ductile from brittle behavior, nor does it validate the criterion on experimentally known ductile or brittle intermetallics of the same C1b/L21 classes. This is not merely a missing literature citation. The paper's own benchmark data (Table 3) give rRice for ductile BCC metals: Li 0.157, Na 0.239, V 0.287, Nb 0.330. The three headline candidates have rRice = 0.44, 0.47, and 0.55 (Table 4), substantially above all four known ductile benchmarks. If the Rice criterion is monotonic, these values place the candidates on the brittle side of the same scale, not the ductile side; if the criterion is not transferable across crystal classes, that transferability must be shown rather than assumed. Without an empirically grounded cutoff, statements such as possesses the most favorable rRice = 0.44 and low Rice's ratio are relative, not evidence of ductility. The caveat that Pugh and Pettifor criteria are unreliable for anisotropic systems does not repair this: the Rice analysis is used as the decisive test, and it is uncalibrated at the exact point where the qualitative conclusion flips.","agreement_with_reader":"agree"},"referee_report":{"model":"deepseek-v4-flash","summary":"The manuscript builds a first-principles high-throughput workflow combining elastic-constant calculations (Born expansion vs. finite displacements) and generalized stacking fault energy/surface energy calculations to screen the supercond-EPW database for ductile, phonon-mediated superconductors. After computing Pugh and Pettifor ratios for 250 materials, the authors calculate Rice ratios for seven half- and full-Heusler candidates and identify HfPd2Al, TiRuSb, and ZrNi2Ga as the most promising ductile superconductors, with predicted isotropic Tc values of 6.80 K, 12.88 K, and 8.23 K. The paper also introduces composite ductility indicators c and c* and an approximate Pugh-Pettifor relation for anisotropic hexagonal/trigonal materials.","tokens_in":22548,"tokens_out":7458,"duration_ms":64170,"significance":"If the ductility classification is validated, the paper would be a valuable contribution: it provides an open AiiDA workflow (aiida-mechanical), carefully benchmarks the finite-displacement elastic tensors and GSFE calculations against literature values, and demonstrates the need to go beyond linear elastic indicators for screening. The honest discussion of the limitations of Pugh and Pettifor criteria for anisotropic structures is a strength. However, the central claim that the three Heusler compounds are ductile superconductors rests entirely on Rice-ratio values (0.44-0.55) that are presented without a calibrated ductile/brittle threshold and that lie above the paper's own reference values for ductile BCC metals (0.16-0.33) and FCC metals (0.09-0.21).","major_comments":[{"comment":"The ductility classification is not calibrated. No value of rRice is stated as separating ductile from brittle behavior, and no validation is provided on experimentally known ductile or brittle C1b/L21 intermetallics. More importantly, the paper's own benchmark data contradict the ductile assignment: the ductile BCC metals in Table 3 have rRice = 0.157 (Li), 0.239 (Na), 0.287 (V), and 0.330 (Nb), and the FCC metals in Table 2 have rRice between roughly 0.09 and 0.21, while the three headline candidates have rRice = 0.44, 0.47, and 0.55. If rRice is a monotonic ductility indicator, these values place the candidates on the brittle side of the same scale; if the criterion is not transferable to ordered intermetallics, that transferability must be demonstrated. As written, statements such as 'the most favorable rRice=0.44' are relative comparisons, not evidence of ductility, and the central conclusion is not supported.","section":"Section 2, Eq. (22)-(23), Table 4"},{"comment":"The composite indicators c and c* are constructed from dataset averages and used to rank and select candidates, but the text does not discuss how robust the ranking is to this normalization or to the inclusion of anisotropic materials for which the authors explicitly state that Pugh and Pettifor criteria are unreliable. Because the top-39 list contains many layered/hexagonal materials, the screen should be presented as a heuristic pre-filter rather than a quantitative ductility measure, and the dependence of the final shortlist on the dataset composition should be checked or at least discussed.","section":"Section 2, Eq. (19) and Eq. (23), Table 1"}],"minor_comments":[{"comment":"The empirical slope of -0.74 for all 250 materials and the analytical slope of -5/3 for isotropic cubic materials are distinguished, but the text could clarify that Eq. (10) and (11) apply only to cubic systems and that the dashed green line is a global fit.","section":"Fig. 2 and surrounding text"},{"comment":"The term 'high-Tc' is used for predicted Tc values of 6.8-12.9 K; this may be misleading and should be reworded to 'promising' or 'moderately high' predicted Tc, particularly because the paper is aimed at practical superconductors.","section":"Abstract and Conclusion"},{"comment":"Adding the derived rRice values directly in the tables (or in a supplementary table) would make the calibration issue transparent and help readers evaluate the ductility claim.","section":"Table 3 and Table 4"},{"comment":"The approximate relation for hexagonal/trigonal materials would benefit from a statement of how many materials in the database actually satisfy assumptions (C11,C12,C66 >> C33,C13,C44 and C12/C11 ~ 0.3), since Fig. 2 shows the line but not the goodness of fit.","section":"Eq. (18)"},{"comment":"There are minor typographical issues, including 'V oigt' (Voigt), 'Allen-Dyne' (Allen-Dynes), and inconsistent capitalization of 'Pettifor's criterion'; these should be corrected.","section":"Throughout"}],"recommendation":"major_revision","confidential_remarks":"The manuscript fits the journal scope and the computational workflow is a genuine asset. The decisive issue is the uncalibrated Rice-ratio threshold; once the authors calibrate it on known ductile/brittle intermetallics or demonstrate transferability, the central claim can be assessed. I would not reject the paper because this is a scoped, fixable validation gap rather than an internal inconsistency."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"The screening itself is well done: first mechanical assessment of the supercond-EPW database, a careful Born-expansion versus finite-displacement comparison with a real convergence analysis, and a GSFE workflow benchmarked on FCC metals, BCC metals, and ionic crystals. The composite indicators c and c* are new, the code is public, and the authors are honest about restricting GSFE work to cubic systems and about the unreliability of Pugh and Pettifor for anisotropic materials. Credit where due.\n\nThe soft spot is the load-bearing one. The paper never states the Rice-ratio value that separates ductile from brittle, and it never validates the criterion on known ductile or brittle intermetallics of the C1b/L21 classes. Worse, the paper's own benchmarks in Table 3 give rRice for ductile BCC metals: Li 0.157, Na 0.239, V 0.287, Nb 0.330. The three headline candidates have rRice = 0.44, 0.47, and 0.55. If the Rice criterion is monotonic, these values sit on the brittle side of the same scale. If it is not transferable across crystal classes, that transferability must be shown. Calling rRice = 0.44 \"most favorable\" is relative, not evidence of ductility. This is not a missing citation; it is an uncalibrated decision boundary at the exact point where the qualitative conclusion flips.\n\nMinor complaints: \"high-Tc\" for 6.8–12.9 K is oversold for a field where 20–40 K is routine, and the paper ships no input or output data beyond the code, with no pinned commit. The elastic screening and the GSFE benchmarks are reproducible enough, but the headline claim is not.\n\nThe paper deserves a serious referee because the workflow and the database are useful and the ductility claim is testable. I would send it to review, but the referee should require either a calibrated threshold or a clear statement that the candidates are simply \"relatively favorable\" among the screened set, not ductile in an absolute sense. As written, the central conclusion is not yet supported.","headline":"Solid screening workflow, but the ductile-superconductor claim is undercut by an uncalibrated Rice-ratio threshold that the paper's own benchmarks would place on the brittle side.","tokens_in":23070,"tokens_out":1568,"would_cite":true,"duration_ms":15960,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":["74.25.Ld","74.70.-b"],"model":"deepseek-v4-flash","headline":"The paper predicts that three Heusler-type compounds—HfPd2Al, TiRuSb, and ZrNi2Ga—are simultaneously ductile and superconducting, with predicted isotropic critical temperatures of 6.80 K, 12.88 K, and 8.23 K.","keywords":["ductile superconductors","high-throughput screening","generalized stacking fault energy","Rice's ratio","Pugh's ratio","Pettifor's ratio","Heusler compounds","first-principles elasticity"],"falsifier":"Grow polycrystalline samples of HfPd2Al, TiRuSb, and ZrNi2Ga and deform them in tension or bending: if they fracture before showing measurable plastic strain, or if crack-tip observations show cleavage instead of dislocation emission, the predicted ductility is wrong.","tokens_in":21975,"feed_emoji":"🧲","tokens_out":9330,"duration_ms":80090,"temperature":0.7,"pith_summary":"This paper tries to find superconductors that are also ductile, so they can be bent, drawn, or wound into coils without cracking—a combination many practical superconducting devices need. The authors screen 250 experimentally known superconductors from an existing first-principles database, first computing elastic stiffness, Pugh's ratio, and Pettifor's ratio, then computing generalized stacking-fault energies and surface energies for the most promising cubic candidates to estimate Rice's ratio, the microscopic competition between dislocation slip and crack opening. They conclude that three Heusler-type compounds—HfPd2Al, TiRuSb, and ZrNi2Ga—are on the ductile side of this criterion while retaining predicted isotropic superconducting transition temperatures of 6.80 K, 12.88 K, and 8.23 K. If the criterion transfers to these intermetallics, the paper supplies concrete compounds to test for fracture-resistant superconductors.","feed_headline":"Three known compounds predicted ductile superconductors","feed_subtitle":"Stacking-fault screen of 250 known superconductors flags three flexible candidates for magnets and wires","key_machinery":"The central object is Rice's ratio, $r_{\\mathrm{Rice}} = \\gamma_{\\mathrm{USFE}}/\\gamma_{\\mathrm{surface}}$, the ratio of the unstable stacking-fault energy to the surface energy on the (1-10) slip plane; a lower value means the crystal prefers to emit dislocations rather than open a crack. The unstable stacking-fault energy comes from a generalized stacking-fault energy (GSFE) curve, the energy cost of rigidly shearing one half of the crystal along the slip plane, fitted to a Fourier series with out-of-plane relaxation. The workflow combines this microscopic indicator with Pugh's ratio $G/B$, Pettifor's ratio $(C_{12}-C_{44})/B$, and a proposed combined score $c^* = c - r_{\\mathrm{Rice}}/r_{\\mathrm{Rice,avg}}$ to rank superconducting candidates by ductility.","core_discovery":"The central claim is that ductility and phonon-mediated superconductivity can coexist in specific intermetallic compounds, and that a first-principles workflow can identify them before synthesis. Starting from 250 experimentally known superconductors with predicted critical temperatures, the paper computes elastic tensors by the finite-displacement method and derives Pugh's and Pettifor's ratios. For seven half- and full-Heusler candidates it then computes relaxed unstable stacking-fault energies and surface energies on the (1-10) slip plane. Three compounds—HfPd2Al, TiRuSb, and ZrNi2Ga—emerge with Rice ratios of 0.44, 0.47, and 0.55 and predicted isotropic critical temperatures of 6.80 K, 12.88 K, and 8.23 K, and the paper's combined ductility-superconductivity score ranks them above the other screened materials.","pith_inferences":["A direct experimental test of the workflow would be to measure stacking-fault energies in one of the three compounds by transmission electron microscopy of partial dislocation separations, comparing those measurements with the calculated 674–911 mJ/m2 range.","Extending the Rice-ratio screen to the hexagonal and layered candidates in the database could reveal additional ductile superconductors, but would require handling their multiple competing slip systems, which the paper sets aside as computationally prohibitive.","If synthesis confirms the predictions, neighboring Heusler compositions could be tuned to raise the critical temperature while keeping a low Rice's ratio, turning the screening into a design loop instead of a one-off selection."],"forward_implications":["If the predictions hold, HfPd2Al, TiRuSb, and ZrNi2Ga become concrete test targets for ductile superconducting wire or film, with predicted isotropic critical temperatures of 6.80 K, 12.88 K, and 8.23 K.","The same workflow can be applied to newly synthesized superconductors, since it starts from elastic tensors and stacking-fault energies rather than from synthesis or melting data.","The combined score gives a single ranking number that balances critical temperature, Pugh's ratio, Pettifor's ratio, and Rice's ratio, allowing future screens to compare candidates quantitatively.","Out-of-plane relaxation is essential: it reduces the unstable stacking-fault energy by about 50% for these Heusler compounds, so rigidity-based criteria alone can misclassify ductility.","Because the predicted critical temperature and the elastic ductility indicators are not correlated in the screened set, the two properties can likely be optimized separately in materials design."],"supporting_citations":[{"why":"Supplies the 250 experimentally known superconductors and their predicted critical temperatures that the screening starts from.","marker":"[6]"},{"why":"Defines Pugh's ratio $G/B$ and the conventional brittle-to-ductile threshold used to pre-screen candidates.","marker":"[12]"},{"why":"Defines Pettifor's ratio from Cauchy pressure, with positive values marking ductile cubic crystals.","marker":"[13]"},{"why":"Introduces Rice's ratio $\\gamma_{\\mathrm{USFE}}/\\gamma_{\\mathrm{surface}}$, the microscopic ductility criterion that carries the final screening.","marker":"[28]"},{"why":"Provides the analytic relation between Pugh's and Pettifor's ratios for cubic materials used in Eq. (10).","marker":"[45]"},{"why":"Gives the Born-expansion method for elastic constants from interatomic force constants, which the paper benchmarks against finite displacements.","marker":"[29]"},{"why":"Provides the finite-displacement method used for the elastic tensors that feed the Pugh and Pettifor ratios.","marker":"[30]"}],"fun_headline_variants":["HfPd2Al, TiRuSb, ZrNi2Ga join ductile superconductor club","Screen predicts three known compounds are ductile superconductors","Three known intermetallics tick ductility and superconductivity boxes","High-throughput screen flags ductile superconductor trio","Three previously known superconductors predicted ductile"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The ductile-superconductor identification rests on Rice's ratio being a valid predictor for Heusler intermetallics, but the paper sets no numerical ductile threshold and does not calibrate the criterion against experimentally known ductile or brittle superconductors.","fun_headline_variants_meta":{"raw":{"variants":["HfPd2Al, TiRuSb, ZrNi2Ga join ductile superconductor club","Screen predicts three known compounds are ductile superconductors","Three known intermetallics tick ductility and superconductivity boxes","High-throughput screen flags ductile superconductor trio","Three previously known superconductors predicted ductile"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.000589,"raw_usage":{"total_tokens":2754,"prompt_tokens":928,"completion_tokens":1826,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":544,"completion_tokens_details":{"reasoning_tokens":1738}},"tokens_in":544,"tokens_out":1826,"duration_ms":12006,"temperature":1.0,"reasoning_tokens":1738,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-11T04:13:36.437773+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Grow polycrystalline samples of HfPd2Al, TiRuSb, and ZrNi2Ga and deform them in tension or bending: if they fracture before showing measurable plastic strain, or if crack-tip observations show cleavage instead of dislocation emission, the predicted ductility is wrong.","supporting_citations":[{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Gives the Born-expansion method for elastic constants from interatomic force constants, which the paper benchmarks against finite displacements."},{"cited_title":"Dal Corso, Clean Ir(111) and Pt(111) electronic surface states: A first-principle fully relativistic investiga- tion, Surface Science 637–638 (2015) 106–115","cited_arxiv_id":null,"evidence_quote":"Provides the finite-displacement method used for the elastic tensors that feed the Pugh and Pettifor ratios."}],"review_version":2}