{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"d2661288776e38ffb84a6852aaa67d8448bc27616986bec101f5247a46357135","created":"2026-10-03T07:17:58Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"378dffde42f013ec437962aa38fd827473e1f6a1c8fd698a0314c14c5aa0f667","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"chem.reference-methods.benzene-exact-energy","kind":"well-posed","literature_status":"partially-resolved","n":"1","parents":[],"plain":"Benzene with 30 active electrons in 108 orbitals has a unique exact answer but is too large for brute-force solution. When the best approximate methods were run on it blind in 2020 they did not all agree.","posed_since":"2020","precise":"For benzene at the reference geometry in the cc-pVDZ basis with frozen $1s$ cores (30 electrons in 108 orbitals), determine the full configuration interaction correlation energy to $0.1\\,\\mathrm{m}E_h$ ($E_h$ = Hartree unit, about $627.5\\,\\mathrm{kcal}/\\mathrm{mol}$) and establish which near-exact methods (selected configuration interaction, DMRG, FCIQMC, many-body expanded FCI, high-order coupled cluster) converge to it. An answer is a value with a defensible error bar confirmed by at least two independent methods.","problem_ref":null,"references":"","settled_by":"Two or more independent near-exact methods with controlled extrapolation agreeing within $0.1\\,\\mathrm{mE}_h$.","status_note":"A 2020 blind comparison (Eriksen et al., J. Phys. Chem. Lett., https://doi.org/10.1021/acs.jpclett.0c02621) gave estimates from the leading methods spread over about $1\\,\\mathrm{m}E_{\\mathrm{h}}$, larger than the $0.1\\,\\mathrm{m}E_{\\mathrm{h}}$ target; later work narrowed the spread, but agreement at $0.1\\,\\mathrm{m}E_{\\mathrm{h}}$ is not established in the literature checked.","title":"Near-exact correlation energy of benzene in a standard basis","topic_ref":"db0a74b17cddd433a8529c6f5d0266089a106dbf62dceceaa234267c8c0478e0"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"8157b2674822b5fa63645d87c78f29346f67d804c9fa7b3a31c763d03691071f","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"7454ef021299c762b037c99f6f3ba93a4dc41693e16eb0cefb3698d73b354c5b","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"uywH8v92NY_Q4ILyqLGvokySiEyaLZUfcPzEb8-5c7GeUqjAbols4kct5dH_TeASn8C9ybIerIKrMaDn6DKfAw"},"schema":"pubphys.envelope/1"},"record_hash":"8157b2674822b5fa63645d87c78f29346f67d804c9fa7b3a31c763d03691071f","leaf_index":894}