--- license: cc-by-nc-4.0 tags: - open-science - superconductivity - superconductor-discovery - strongly-correlated - materials-discovery - 2d-materials - twisted-bilayer - moire - hubbard-model - d-wave - machine-learning-for-materials - computational-materials-science - challenge - leaderboard - benchmark - cpu-friendly language: - en pretty_name: "OSC — Open Superconductor Challenge" size_categories: - 1Kx²−y²) pairing estimate and submit it. - **What we do:** verify the top submissions with a precise many-body reference solver. - **Who can join:** anyone — researchers, students, and AI coding agents. --- ## What is the Open Superconductor Challenge? The **Open Superconductor Challenge (OSC)** is a crowd-sourced materials-screening benchmark for **unconventional superconductivity** in two-dimensional (2D) materials. Discovering superconductors experimentally is slow and expensive, so OSC screens candidates *computationally, before the lab*: the community estimates a superconducting-pairing signal for thousands of materials, and a precise reference solver confirms the most promising ones. OSC targets **d-wave (dx²−y²) pairing tendency** — the pairing symmetry associated with cuprates, twisted bilayer graphene, and other strongly-correlated systems — using the doped **Hubbard model** as the effective description. It is hosted by **FINAL-Bench** as an open-science initiative and is designed to be reproducible, hard to game, and accessible without specialized hardware. ## Why OSC matters - **Compute arbitrage:** the crowd screens broadly on laptops; the organizers spend heavy DFT and many-body compute only on the top candidates. This finds promising materials for a fraction of the usual cost. - **Open and fair:** the candidate list, protocol, and baseline tools are fully open (GPL/MIT); only the final verification engine is private, which keeps the ranking un-gameable without hiding the science. - **Reproducible science:** every material carries a provenance trail to C2DB, and winning methods are shared under a contributor license. --- ## Dataset contents | File | Description | |---|---| | `candidates.csv` | The full browsable universe — **4,832** dynamically-stable 2D materials (C2DB-derived) enriched with our tags: chemical family, cost class, is-metal, band gap, and a screening prior. | | `active_challenge.csv` | The **active competition set** (metallic / small-gap materials) with the provided **effective model**: `t` (eV), `U` (eV), `U/t`, and **`nef`** = N(E_F) (states/eV/atom). | | `submissions.csv` | The baseline leaderboard rows and verified anchor scores (the OSC Pairing Index). | | `instrument/osc_instrument.py` | The participant tool — pure Python, no install, runs in seconds on any laptop. | | `instrument/pair_baseline.py` | An open d-wave pair-susceptibility routine to build a competitive method on. | | `PROVENANCE.md` | Data source and license details (C2DB, CC-BY-NC 4.0). | ## The effective model (what you receive per material) For every active material OSC provides a downfolded **Hubbard effective model**: - **`t`** — nearest-neighbor hopping (eV), from the DFT band structure. - **`U`** — on-site Coulomb interaction (eV); the challenge fixes the strongly-correlated regime at **U/t = 8** (cuprate convention). - **`N(E_F)`** (`nef`) — density of states at the Fermi level (states/eV/atom), the first-order BCS indicator: higher N(E_F) → stronger pairing tendency. Your task is to do better than the first-order screen by computing an actual, **material-specific** d-wave pairing estimate. --- ## How to participate (light track — any laptop, no install) You do **not** need a GPU or any installation for the light track. An AI coding agent (Claude Code, Codex) can also do every step for you — just point it at this challenge. **1. Sign in** with Hugging Face on the [OSC Leaderboard Space](https://huggingface.co/spaces/FINAL-Bench/OSC-Leaderboard) — this verifies your identity so entries can't be posted under someone else's handle. **2. Get the instrument** (pure Python — Windows / Linux / macOS, nothing to install): ```bash huggingface-cli download FINAL-Bench/OSC-Superconductor \ instrument/osc_instrument.py instrument/pair_baseline.py \ --repo-type dataset --local-dir osc cd osc/instrument ``` **3. Pick a material and run:** ```bash python osc_instrument.py --material_id OSC-00129 --author YOUR_NAME # reads the material's (t, U, N(E_F)); prints an OSC Pairing Index on the leaderboard's scale # -> writes submission.json ``` To **compete on the gold track**, edit `estimate_pairing()` with your own many-body method — exact diagonalization (ED), variational Monte Carlo (VMC), DMRG, mean-field, or machine learning — that improves on the first-order N(E_F) screen. **4. Submit your score.** Open the material's card in the **Active Challenge** tab of the Space and submit (you must be signed in), or open a Pull Request adding your `submission.json` under `submissions/` in this dataset. Your provisional score appears on the leaderboard immediately. --- ## Scoring: the OSC Pairing Index The leaderboard reports an **OSC Pairing Index**, a per-material, physically-grounded score: ``` Pairing Index = N(E_F) × A_d(δ_material) × 300 ``` where **A_d(δ)** is the max-distance d-wave (dx²−y²) pair correlation from the organizers' precise 6×6 doped-Hubbard solver **run at each material's DFT band filling δ** (U/t = 8). Because A_d depends strongly on doping, A_d(δ) traces a **d-wave dome** peaking near optimal hole doping (δ ≈ 0.25–0.30) and vanishing at half-filling and heavy overdoping — so materials at different fillings get genuinely different amplitudes. A_d ≤ 0 (no d-wave order) scores 0. The ×300 is a single, monotone readability factor used **everywhere** (instrument, baseline, verified). The full A_d(δ) table is in `scoring_meta.json`; the pipeline is in `pipeline/`. - **Baseline** — N(E_F) × the published A_d(δ) for the material; the bar to beat (reproduces the anchor). - **Provisional** — your submitted estimate, on the same scale; appears instantly. - **Verified** — the organizers' precise solver at the material's filling sets the official rank. **Honest interpretation:** the index is a **d-wave pair-correlation screening indicator**, not a guaranteed critical temperature (Tc) or a confirmed superconductor. Two caveats we state plainly: - **Not proven interaction-driven pairing.** A_d comes from a d-wave-biased variational (NQS/AGP) wavefunction, so it measures the pair correlation that a paired trial state sustains — not an unbiased proof that the Hubbard model itself wants d-wave. Independent exact-diagonalization (ED) cross-checks (contributed by participants) and our own control runs (d-wave vs Fermi-sea on a common 4×4 cluster) show the enhancement over the non-interacting case is **not monotonic and is dominated by finite-size effects** — consistent with the modern result that the pure 2D Hubbard model shows no robust d-wave superconductivity at U/t = 8 (Qin et al., *Science* 2020). Treat the A_d(δ) "dome" as partly a finite-size/ansatz feature. - **Single-band approximation** (N(E_F) and δ from DFT, t from the active-band width, U/t = 8 as a control). Use the index to **rank and prioritize candidates**, not to claim superconductivity. You compete by computing a better, material-specific pairing estimate with your own many-body method. ### Why top scores cluster near the baseline — and the only two ways to exceed it Every submission is scored on the material's **real** values — our pipeline N(E_F) and A_d at the material's **real DFT filling** — regardless of any N(E_F)/A_d/δ a submission claims. A claimed value is recorded (as `claimed`) but never ranked as-is. So the leaderboard tops out at the single highest-scoring active material (currently ≈ 22), and many entries tie there. **Inflated claims are automatically scored down to the material's real value** — this is deliberate, to keep the ranking un-gameable. There are exactly two honest ways to go higher: 1. **Discovery track** — propose a *new* material (outside the active set) with a higher N(E_F) × A_d(δ). We downfold it ourselves with the published pipeline (DFT SCF → downfolding → solver); if its real value exceeds the baseline, your entry leads. New proposals are **queued for organizer downfolding** and posted when the DFT completes. *Caveat:* for multi-band metals the active-band selection can shift the filling δ (and therefore the score) substantially; such cases are flagged and the band choice is refined before a score is finalized. 2. **Method track (verified)** — a *reproducible* method that genuinely improves the estimate for a material. See the rules below. ## Gold / Method track — procedure and how it is judged **How to submit (Gold / Method):** 1. **Register** your score and method name on Hugging Face (a PR under `submissions/`, or on the Space). 2. **Email a reproducibility package** to the organizers: the code, frozen checkpoint/config, a `run_*.sh` that reproduces the number, a SHA256 manifest, and any independent-seed robustness evidence. Do **not** rescale or empirically fit to the published references. 3. We **independently reproduce** it. If it reproduces, it is recorded as a **verified-reproducible Method contribution** (credited, with a badge). **How the Method rank is decided — read this before expecting a higher score:** Method standing is judged by **reproducibility and agreement with the independent reference (exact diagonalization)** — **not** by the raw size of a claimed A_d. This is deliberate: a d-wave-biased variational wavefunction can always report a larger A_d, and independent multi-size ED shows that the **absolute** d-wave amplitude is *not size-converged* (see `validation/`), so a bigger A_d is not, by itself, "more correct." Concretely: - A claimed A_d larger than our solver value does **not** automatically beat the baseline on the leaderboard. The displayed score stays canonical. - A reproduced method can **raise (or lower) a material's official A_d only once the ED calibration shows it is closer to the exact answer**; that correction then applies to everyone (and the contributor is credited / eligible for co-authorship). - Until the calibration is settled, verified methods receive recognition (badge, Method shortlist), and absolute-score credit is held — not denied, just deferred to a calibrated basis. **Multi-band materials:** when more than one band crosses E_F, the active-band choice can shift the filling δ and hence the score; such materials are marked **provisional (band selection being refined)** and are not finalized until resolved — this applies to the material for every submitter. ## Tracks & prizes (total US $3,000) | Prize | Amount | Awarded to | |---|---|---| | **Grand** | $1,500 | highest **verified** d-wave tendency (any material) | | **Best Method (Gold)** | $1,000 | top **verified** score with an open-sourced method | | **Best Discovery (Open)** | $500 | best **verified** new material you propose | One cash prize per person (the runner-up succeeds on overlap). On overlap, the higher prize is kept with precedence **Grand > Best Method > Best Discovery**. **"Per person" means per person or team (real identity)** — multiple accounts by the same person count as one entrant. For **Discovery**, the award goes to the **first** entrant to propose a new material that then verifies; once a material is added to the active set, later identical submissions get its canonical score but not the Discovery credit. Ranks 2–5 and all valid entrants receive **co-authorship, hall-of-fame listing, and leaderboard credit**. --- ## Frequently asked questions ### Do I need a GPU or to install anything? No. The light track is a single pure-Python script that runs in seconds on any laptop CPU — Windows, Linux, or macOS. A GPU only helps if you choose the advanced full-stack track. ### What exactly am I predicting? A **d-wave (dx²−y²) superconducting pairing tendency** for a given 2D material, from its effective Hubbard model. This is a screening signal, not a measured critical temperature. ### Does the #1 material mean the best superconductor? It means the strongest d-wave pairing *tendency by our first-order screen* — the top candidate to investigate. It is not a confirmed superconductor or the highest Tc. ### How are winners verified? The organizers run a precise strongly-correlated (NQS/GFMC-class) solver at each material's DFT band filling to get its d-wave amplitude A_d(δ); the verified score is N(E_F) × A_d(δ) × 300. The solver's inputs and its A_d(δ) table are published, so every verified score is reproducible; only the internal solver implementation is withheld to keep the ranking hard to game. ### Do I have to reveal my method or code? No — you submit only result numbers. Only prize winners share reproducible code, under a contributor license. The verification engine runs on our servers and is never distributed, which is what keeps the ranking un-gameable. ### Where does the data come from? Materials derive from the **Computational 2D Materials Database (C2DB)** under CC-BY-NC 4.0. We add value (family tags, cost classes, effective models, screening priors) and cite the source in `PROVENANCE.md`. ### When does the challenge close? **Season 1 closes 31 December 2026, 23:59 KST.** The leaderboard, instrument, and authenticated submission are live now, and the active set is being expanded. ### Can an AI agent enter for me? Yes. Point an AI coding agent (Claude Code / Codex) at the challenge and it can download the instrument, compute a score, and submit on your behalf. --- ## Keywords superconductor discovery · unconventional superconductivity · d-wave pairing · 2D materials · twisted bilayer · moiré materials · strongly-correlated electrons · doped Hubbard model · density of states at the Fermi level · N(E_F) · computational materials science · machine learning for materials · open-science challenge · Hugging Face leaderboard · CPU-only benchmark · crowd-sourced materials screening. ## Citation & license - **Baseline tools, downfolding pipeline, and protocol:** open source (`instrument/`, `pipeline/`). - **Materials & derived models:** derived from C2DB under **CC-BY-NC 4.0** — see `PROVENANCE.md`. - **Non-commercial:** because the source data is CC-BY-NC, OSC is a **non-commercial academic** challenge; prizes are research awards (recognition + co-authorship + honorarium), not a commercial use of the data. Any commercial use of the underlying data must be cleared with C2DB. ## Independent validation & contributors OSC's verification solver is cross-checked against independent exact diagonalization (ED). The first such cross-check — a common 4×4 cluster (U/t = 8) ED table with U = 0 controls — was contributed by **Ku-ku** and is published at `validation/comparison_4x4_ED_vs_VMC.md` (CC-BY-NC 4.0, with attribution). It independently reproduced all 64 verified scores from the published pipeline, and checked the particle-hole relation on the **4×4** cluster at maximal distance (R = √5, (2,2); agreement ≤ 3.3e-14) — the 6×6 R = (3,3) case was not computed. Because our 6×6 VMC A_d and the 4×4 ED values are essentially uncorrelated across filling on a single cluster size, ED is used (as agreed) to correct **sign and rank** first, not absolute values, until the size dependence converges. Contributors of verified ED/method references are credited in `validation/` and the README, and are eligible for co-authorship on the challenge report. We thank the participants and reviewers whose scrutiny made the scoring honest. - **Verification engine:** operated by the organizers (FINAL-Bench), not distributed. If OSC helps your work, please link the challenge Space (https://huggingface.co/spaces/FINAL-Bench/OSC-Leaderboard) and credit **FINAL-Bench — Open Superconductor Challenge**. *Hosted by FINAL-Bench as an open-science initiative. Season 1 is open until 31 December 2026 (23:59 KST). Star and watch to follow the leaderboard.*