{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"ae515f546d5a2a74a1a70ef97b14955198b4adaf962d7671fcf553d73766212e","created":"2026-10-03T07:17:58Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"439b04ffb4456eb1239af42e394931dea2989fce46ca5a4e8814cdbd34114f43","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"chem.strong-correlation.iron-porphyrin-spin","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"An iron atom held flat inside a ring-shaped molecule called a porphyrin can have its electron spins in a low, middle or high configuration. Different high-level methods give different answers for which configuration has the lowest energy.","posed_since":"","precise":"For the isolated Fe(II) porphine molecule, determine the adiabatic energy differences among the lowest $S = 0, 1 \\text{ and } 2$ states (each at its own optimized geometry, zero-point corrected) to 1 kcal/mol, together with the vertical gaps at a stated common $D4h$ geometry, including the sign of the triplet-quintet gap. An answer is agreement among independent wavefunction methods (coupled cluster with high excitations, DMRG plus perturbation theory, quantum Monte Carlo) extrapolated to the complete basis set limit.","problem_ref":null,"references":"","settled_by":"Mutually consistent complete-basis extrapolations from at least two unrelated near-exact methods, cross-checked against gas-phase or matrix-isolation spectroscopy.","status_note":"","title":"Spin state ordering of iron(II) porphyrin","topic_ref":"847ae9aefb60fe69f3c180c7eb035001e6a5d3b47d929d0e616702d75f440a19"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"dccced891ad9c7c0576e819faa245e584a1e003a106fed804939ffe16fbdc9d8","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"bc219b7bc962fe0484e9737e26dc12cf967aad49653444508608876bff2300eb","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"tU47oMxZoBcK41TGMmRhj0LJPL3oq4CS1pq9fpqnen7h87B7cv9qD_fLzIdJ6nb2j0mdFsncEtVOcZgkn_YbCA"},"schema":"pubphys.envelope/1"},"record_hash":"dccced891ad9c7c0576e819faa245e584a1e003a106fed804939ffe16fbdc9d8","leaf_index":898}