{"paper":{"title":"Seniority-zero Quadratic Canonical Transformation Theory","license":"http://creativecommons.org/licenses/by-nc-nd/4.0/","headline":"Seniority-zero quadratic canonical transformation allows approximate four-body terms to improve accuracy for strongly correlated electrons.","cross_cats":[],"primary_cat":"physics.chem-ph","authors_text":"Daniel F. Calero-Osorio, Paul W. Ayers","submitted_at":"2026-04-29T01:12:18Z","abstract_excerpt":"We propose a method to solve the Schr\\\"odinger equation for systems with static/strong electron correlation using Hamiltonian transformations. Building on our previous work on seniority-zero canonical transformation theory, which seeks a unitary transformation that maps the Hamiltonian into the seniority-zero space, this method presents an alternative way of evaluating the Baker--Campbell--Hausdorff (BCH) expansion based on quadratic canonical transformation theory. The extension aims to relax the small-generator constraint by allowing approximate four-body contributions in the expansion, thus"},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"Numerical tests reveal that the seniority-zero quadratic canonical transformation method (SZ-QCT) delivers good accuracy, with most errors within chemical accuracy. In particular, SZ-QCT shows sub-millihartree errors in cases where larger generators are needed to recover the residual dynamic correlation.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"The assumption that approximate four-body contributions can be retained in the BCH expansion while preserving the validity and accuracy of the seniority-zero mapping without introducing uncontrolled errors or violating the unitary transformation properties.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"SZ-QCT relaxes the small-generator limit of prior seniority-zero methods by retaining approximate four-body operators, yielding sub-millihartree accuracy for strongly correlated systems at O(N^8) scaling.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Seniority-zero quadratic canonical transformation allows approximate four-body terms to improve accuracy for strongly correlated electrons.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"8079004a231e394ddb925799d3e3cd6a5e0849e00e0f2f52ab4ec5606fa19a26"},"source":{"id":"2604.26202","kind":"arxiv","version":1},"verdict":{"id":"d598fa11-905b-41c6-a91d-2624149d2866","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-07T12:59:22.485436Z","strongest_claim":"Numerical tests reveal that the seniority-zero quadratic canonical transformation method (SZ-QCT) delivers good accuracy, with most errors within chemical accuracy. In particular, SZ-QCT shows sub-millihartree errors in cases where larger generators are needed to recover the residual dynamic correlation.","one_line_summary":"SZ-QCT relaxes the small-generator limit of prior seniority-zero methods by retaining approximate four-body operators, yielding sub-millihartree accuracy for strongly correlated systems at O(N^8) scaling.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"The assumption that approximate four-body contributions can be retained in the BCH expansion while preserving the validity and accuracy of the seniority-zero mapping without introducing uncontrolled errors or violating the unitary transformation properties.","pith_extraction_headline":"Seniority-zero quadratic canonical transformation allows approximate four-body terms to improve accuracy for strongly correlated electrons."},"integrity":{"clean":false,"summary":{"advisory":0,"critical":2,"by_detector":{"doi_compliance":{"total":2,"advisory":0,"critical":2,"informational":0}},"informational":0},"endpoint":"/pith/2604.26202/integrity.json","findings":[{"note":"Identifier '10.1016/s0065-3276(08)60045-0' is syntactically valid but the DOI registry (doi.org) returned 404, and Crossref / OpenAlex / internal corpus also have no record. 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