{"paper":{"title":"Transition-Potential Coupled Cluster II: Optimization of the Core Orbital Occupation Number","license":"","headline":"Element-specific fractional core occupations let transition-potential coupled cluster match experimental x-ray absorption spectra of nucleobases with smaller overall shifts than standard EOM-CCSD.","cross_cats":[],"primary_cat":"physics.chem-ph","authors_text":"Devin A. Matthews, Megan Simons","submitted_at":"2022-04-11T22:05:51Z","abstract_excerpt":"The issue of orbital relaxation in computational core-hole spectroscopy, specifically x-ray absorption, has been a major problem for methods such as equation-of-motion coupled cluster with singles and doubles (EOM-CCSD). The transition-potential coupled cluster (TP-CC) method is utilized to address this problem by including an explicit treatment of orbital relaxation via the use of reference orbitals with a fractional core occupation number. The value of the fractional occupation parameter $λ$ was optimized for both TP-CCSD and XTP-CCSD methods in an element-specific manner due to the differen"},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"TP-CCSD reproduces the valence region well and requires smaller overall energy shifts in comparison to EOM-CCSD, while also improving on the relative position and intensities of several absorption peaks.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"That an element-specific but molecule-independent fractional occupation λ optimized on atomic or small-molecule data remains optimal for larger organic molecules such as adenine and thymine.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"Element-specific optimization of the fractional occupation λ in TP-CCSD reduces energy shifts and improves valence-region peak positions and intensities for K-edge spectra of adenine and thymine.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Element-specific fractional core occupations let transition-potential coupled cluster match experimental x-ray absorption spectra of nucleobases with smaller overall shifts than standard EOM-CCSD.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"216a9b92cec9b77b4e3f3fba304ff5f4d372824118fe460bb68500d024ddda85"},"source":{"id":"2204.05425","kind":"arxiv","version":1},"verdict":{"id":"4f7a5af2-0eef-436f-93f1-69e5efb20327","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-14T22:05:27.407514Z","strongest_claim":"TP-CCSD reproduces the valence region well and requires smaller overall energy shifts in comparison to EOM-CCSD, while also improving on the relative position and intensities of several absorption peaks.","one_line_summary":"Element-specific optimization of the fractional occupation λ in TP-CCSD reduces energy shifts and improves valence-region peak positions and intensities for K-edge spectra of adenine and thymine.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"That an element-specific but molecule-independent fractional occupation λ optimized on atomic or small-molecule data remains optimal for larger organic molecules such as adenine and thymine.","pith_extraction_headline":"Element-specific fractional core occupations let transition-potential coupled cluster match experimental x-ray absorption spectra of nucleobases with smaller overall shifts than standard EOM-CCSD."},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":1,"snapshot_sha256":"f6325aeb64736cfdc6bc400eab915a527f409bb7e6cc8ded76c21531be881dd5"},"author_claims":{"count":1,"strong_count":1,"snapshot_sha256":"5e3b23b793a24ad44d50f012bed3c12f7c9e9c566d826ad85b79440943422c6c"},"builder_version":"pith-number-builder-2026-05-17-v1"}