{"record_type":"pith_number_record","schema_url":"https://pith.science/schemas/pith-number/v1.json","pith_number":"pith:2011:DMILMI562U2J3QSYCBBVM7NM44","short_pith_number":"pith:DMILMI56","schema_version":"1.0","canonical_sha256":"1b10b623bed5349dc2581043567dace71f84a3e184b0e0415a859c954398ce8a","source":{"kind":"arxiv","id":"1103.0108","version":3},"attestation_state":"computed","paper":{"title":"Anharmonic stabilization of the high-pressure simple cubic phase of calcium","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"cond-mat.supr-con","authors_text":"Aitor Bergara, Bruno Rousseau, Ion Errea","submitted_at":"2011-03-01T09:04:09Z","abstract_excerpt":"The phonon spectrum of the high-pressure simple cubic phase of calcium, in the harmonic approx- imation, shows imaginary branches that make it mechanically unstable. In this letter, the phonon spectrum is recalculated using density-functional theory (DFT) ab initio methods fully including anharmonic effects up to fourth order at 50 GPa. Considering that perturbation theory cannot be employed with imaginary harmonic frequencies, a variational procedure based on the Gibbs- Bogoliubov inequality is used to estimate the renormalized phonon frequencies. The results show that strong quantum anharmon"},"verification_status":{"content_addressed":true,"pith_receipt":true,"author_attested":false,"weak_author_claims":0,"strong_author_claims":0,"externally_anchored":false,"storage_verified":false,"citation_signatures":0,"replication_records":0,"graph_snapshot":true,"references_resolved":false,"formal_links_present":false},"canonical_record":{"source":{"id":"1103.0108","kind":"arxiv","version":3},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"cond-mat.supr-con","submitted_at":"2011-03-01T09:04:09Z","cross_cats_sorted":[],"title_canon_sha256":"492f814dfe034ced0ae62c2e0a128fe1f95b08f88d233793cc2eb8bb9a2aab12","abstract_canon_sha256":"f5173be38937f579139bb5803da05b143b63188e6bd5453407ff38e18b8cc113"},"schema_version":"1.0"},"receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-18T02:03:01.852816Z","signature_b64":"nK7+SIgw/4M6ar3cB0/5dvKJKR7SQtb6ZFf8/Lgp7wf4qCuzlQ6y+IDsiz7ll+oRa1zpCPIDK/CQMFfZ+EESCg==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"1b10b623bed5349dc2581043567dace71f84a3e184b0e0415a859c954398ce8a","last_reissued_at":"2026-05-18T02:03:01.852108Z","signature_status":"signed_v1","first_computed_at":"2026-05-18T02:03:01.852108Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"graph_snapshot":{"paper":{"title":"Anharmonic stabilization of the high-pressure simple cubic phase of calcium","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"cond-mat.supr-con","authors_text":"Aitor Bergara, Bruno Rousseau, Ion Errea","submitted_at":"2011-03-01T09:04:09Z","abstract_excerpt":"The phonon spectrum of the high-pressure simple cubic phase of calcium, in the harmonic approx- imation, shows imaginary branches that make it mechanically unstable. In this letter, the phonon spectrum is recalculated using density-functional theory (DFT) ab initio methods fully including anharmonic effects up to fourth order at 50 GPa. Considering that perturbation theory cannot be employed with imaginary harmonic frequencies, a variational procedure based on the Gibbs- Bogoliubov inequality is used to estimate the renormalized phonon frequencies. The results show that strong quantum anharmon"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1103.0108","kind":"arxiv","version":3},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"},"aliases":[{"alias_kind":"arxiv","alias_value":"1103.0108","created_at":"2026-05-18T02:03:01.852227+00:00"},{"alias_kind":"arxiv_version","alias_value":"1103.0108v3","created_at":"2026-05-18T02:03:01.852227+00:00"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1103.0108","created_at":"2026-05-18T02:03:01.852227+00:00"},{"alias_kind":"pith_short_12","alias_value":"DMILMI562U2J","created_at":"2026-05-18T12:26:26.731475+00:00"},{"alias_kind":"pith_short_16","alias_value":"DMILMI562U2J3QSY","created_at":"2026-05-18T12:26:26.731475+00:00"},{"alias_kind":"pith_short_8","alias_value":"DMILMI56","created_at":"2026-05-18T12:26:26.731475+00:00"}],"events":[],"event_summary":{},"paper_claims":[],"inbound_citations":{"count":0,"internal_anchor_count":0,"sample":[]},"formal_canon":{"evidence_count":0,"sample":[],"anchors":[]},"links":{"html":"https://pith.science/pith/DMILMI562U2J3QSYCBBVM7NM44","json":"https://pith.science/pith/DMILMI562U2J3QSYCBBVM7NM44.json","graph_json":"https://pith.science/api/pith-number/DMILMI562U2J3QSYCBBVM7NM44/graph.json","events_json":"https://pith.science/api/pith-number/DMILMI562U2J3QSYCBBVM7NM44/events.json","paper":"https://pith.science/paper/DMILMI56"},"agent_actions":{"view_html":"https://pith.science/pith/DMILMI562U2J3QSYCBBVM7NM44","download_json":"https://pith.science/pith/DMILMI562U2J3QSYCBBVM7NM44.json","view_paper":"https://pith.science/paper/DMILMI56","resolve_alias":"https://pith.science/api/pith-number/resolve?arxiv=1103.0108&json=true","fetch_graph":"https://pith.science/api/pith-number/DMILMI562U2J3QSYCBBVM7NM44/graph.json","fetch_events":"https://pith.science/api/pith-number/DMILMI562U2J3QSYCBBVM7NM44/events.json","actions":{"anchor_timestamp":"https://pith.science/pith/DMILMI562U2J3QSYCBBVM7NM44/action/timestamp_anchor","attest_storage":"https://pith.science/pith/DMILMI562U2J3QSYCBBVM7NM44/action/storage_attestation","attest_author":"https://pith.science/pith/DMILMI562U2J3QSYCBBVM7NM44/action/author_attestation","sign_citation":"https://pith.science/pith/DMILMI562U2J3QSYCBBVM7NM44/action/citation_signature","submit_replication":"https://pith.science/pith/DMILMI562U2J3QSYCBBVM7NM44/action/replication_record"}},"created_at":"2026-05-18T02:03:01.852227+00:00","updated_at":"2026-05-18T02:03:01.852227+00:00"}