{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"5f26c102af62bb97bceb070f7e4368c44ca24cf1a469304afc58d44c4c857f8a","created":"2026-10-03T07:17:57Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"0525fc2dbd8c953ff01b8ea5fb3e8d5a6296ae4c95d56420bad9665cd58c7395","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"bio.lc-defects.twist-bend-mechanism","kind":"phenomenon","literature_status":"contested","n":"1","parents":[],"plain":"Bent-shaped molecules can form a nematic whose alignment spirals with a pitch of only about 100 Angstrom, the twist-bend nematic. Whether it forms because bending becomes energetically favourable or because of hidden polar order is disputed.","posed_since":"2013","precise":"The twist-bend nematic $N_{\\mathrm{TB}}$ (heliconical director, pitch about $8e-7\\ \\text{to}\\ 1e-6\\,\\mathrm{cm}$ in CB7CB) was predicted from a negative bend elastic constant $K_{33} < 0$ and alternatively explained through coupling to local polar order or flexoelectricity. Determine which mechanism stabilizes $N_{\\mathrm{TB}}$ and derive its coarse-grained elasticity (whether it behaves as a pseudo-layered smectic) from measured elastic constants and structure.","problem_ref":null,"references":"","settled_by":"Measurement of the elastic constants and polar order through the $N$ to $N_{\\mathrm{TB}}$ transition, compared with predictions of the competing theories.","status_note":"","title":"What stabilizes the twist-bend nematic phase","topic_ref":"29d09ff696c4d5fbc16d256673cc371d0985ecc50fd7d3a13d3921e10e53dfd6"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"8c54e8380ad32cdaf0505efd8ae29121f5c10fb097b2e48a537f53c5556824fc","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"43b59915c869fcc410e93c8851545dcacca7342cfdcf72bf0dbae3d61801212a","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"Z4Ca00_6DykuAAwK8TmqtFyRlB2MiprrhxILHVn5UhUg-Mim1Q89awaqT-iiCyLkZBjrBuq0h5dZIJZw7OmQBg"},"schema":"pubphys.envelope/1"},"record_hash":"8c54e8380ad32cdaf0505efd8ae29121f5c10fb097b2e48a537f53c5556824fc","leaf_index":796}