{"paper":{"title":"Quantifying the impact of the Tamm-Dancoff approximation on the computed spectra of transition-metal systems","license":"","headline":"Tamm-Dancoff approximation produces core-level spectra of transition-metal complexes that match full TDDFT results to high accuracy.","cross_cats":[],"primary_cat":"physics.chem-ph","authors_text":"Daniel R. Nascimento, Matthew N. Ward, Megan Simons, Muhammed A. Dada, Sarah Pak","submitted_at":"2025-06-30T23:10:01Z","abstract_excerpt":"The Tamm-Dancoff Approximation (TDA) offers a computationally efficient alternative to full linear-response Time-Dependent Density Functional Theory (TDDFT) for calculating electronic excited states, particularly in large molecular systems. By neglecting the coupling between excitation and de-excitation channels, TDA simplifies the TDDFT response equations into a Hermitian form. This not only reduces computational cost but also eliminates numerical instabilities that can arise in the full non-Hermitian formalism. While TDA has been widely explored for valence excitations, its reliability for t"},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"For core-level excitations, TDA yields excitation energies and oscillator strengths nearly indistinguishable from those obtained with full TDDFT.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"The transition-metal species examined are representative of the broader class of complexes for which the negligible de-excitation contribution will continue to hold.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"TDA produces excitation energies and oscillator strengths for transition-metal core-level spectra that are nearly identical to full TDDFT because de-excitation amplitudes become negligible at high energies.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Tamm-Dancoff approximation produces core-level spectra of transition-metal complexes that match full TDDFT results to high accuracy.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"010666362d925da900a4928aa1b33bf9b2aaf45c732211bf68c4a070be2d5542"},"source":{"id":"2507.00314","kind":"arxiv","version":1},"verdict":{"id":"7db48c79-76c4-49e2-88fe-7997a7b8bba6","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-14T22:02:41.805379Z","strongest_claim":"For core-level excitations, TDA yields excitation energies and oscillator strengths nearly indistinguishable from those obtained with full TDDFT.","one_line_summary":"TDA produces excitation energies and oscillator strengths for transition-metal core-level spectra that are nearly identical to full TDDFT because de-excitation amplitudes become negligible at high energies.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"The transition-metal species examined are representative of the broader class of complexes for which the negligible de-excitation contribution will continue to hold.","pith_extraction_headline":"Tamm-Dancoff approximation produces core-level spectra of transition-metal complexes that match full TDDFT results to high accuracy."},"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"}