{"paper":{"title":"Accurate core-excited states via inclusion of core triple excitations in similarity-transformed EOM theory","license":"","headline":"Including triples only in the core ionization step of STEOM yields K-edge excitation energies nearly as accurate as full triples methods.","cross_cats":[],"primary_cat":"physics.chem-ph","authors_text":"Devin A. Matthews, Megan Simons","submitted_at":"2022-03-17T17:42:41Z","abstract_excerpt":"The phenomenon of orbital relaxation upon excitation of core electrons is a major problem in the linear-response treatment of core-hole spectroscopies. Rather than addressing relaxation through direct dynamical correlation of the excited state via equation-of-motion coupled cluster theory (EOMEE-CC), we extend the alternative similarity-transformed equation-of-motion coupled cluster theory (STEOMEE-CC) by including the core-valence separation (CVS) and correlation of triple excitations only within the calculation of core ionization energies. This new method, CVS-STEOMEE-CCSD+cT, significantly "},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"CVS-STEOMEE-CCSD+cT significantly improves on CVS-EOMEE-CCSD and unmodified CVS-STEOMEE-CCSD when compared to full CVS-EOM-CCSDT for K-edge core-excitation energies.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"That restricting triples to the core-ionization step captures the dominant orbital-relaxation effect without needing triples in the valence excitation manifold.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"CVS-STEOMEE-CCSD+cT recovers most of the accuracy gain from full triples for core-excitation energies at lower cost by restricting triples to the core-ionization calculation.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Including triples only in the core ionization step of STEOM yields K-edge excitation energies nearly as accurate as full triples methods.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"a61afa3c3b4bd154f8c19ff4f1627362e81ea38e1611cf6cc5f85c52a038b118"},"source":{"id":"2203.09491","kind":"arxiv","version":1},"verdict":{"id":"37ada32a-1faf-43d0-9bda-2bf062182a3e","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-14T22:07:58.491885Z","strongest_claim":"CVS-STEOMEE-CCSD+cT significantly improves on CVS-EOMEE-CCSD and unmodified CVS-STEOMEE-CCSD when compared to full CVS-EOM-CCSDT for K-edge core-excitation energies.","one_line_summary":"CVS-STEOMEE-CCSD+cT recovers most of the accuracy gain from full triples for core-excitation energies at lower cost by restricting triples to the core-ionization calculation.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"That restricting triples to the core-ionization step captures the dominant orbital-relaxation effect without needing triples in the valence excitation manifold.","pith_extraction_headline":"Including triples only in the core ionization step of STEOM yields K-edge excitation energies nearly as accurate as full triples methods."},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":1,"strong_count":1,"snapshot_sha256":"5e3b23b793a24ad44d50f012bed3c12f7c9e9c566d826ad85b79440943422c6c"},"builder_version":"pith-number-builder-2026-05-17-v1"}