{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"ce7e85684067b4b4848f9119329e37595ee6bc5dc390afe95d968d004c37ec7a","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["86f9acae4a5d4803df0e1fd08f217046ce969911fb81c49342f61c1524a312eb","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"6555bbd13ab779d4e9d185a9ea9a23368f4304b3eb0c8b8f850da08ed7b7da17","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"chem.liquid-water.proton-transport-step","kind":"well-posed","literature_status":"contested","n":"2","parents":[],"plain":"Extra hydrogen ions move through water several times faster than other ions by hopping between water molecules. Which molecular step sets the speed of this hopping is not agreed.","posed_since":"","precise":"For an excess proton in liquid water at $300\\,\\mathrm{K}$, identify the rate-limiting step of structural (Grotthuss) diffusion, the relay of the proton from molecule to molecule: hydrogen-bond breaking or forming in the second solvation shell, or motion along the proton-transfer coordinate. An answer is a simulation with path-integral nuclei on a near-quantum-chemical potential that reproduces the measured proton diffusion coefficient (about $9.3 \\times 10^{-5}\\,\\mathrm{cm}^2/\\mathrm{s}$) and its H/D isotope effect and identifies the step from the trajectories.","problem_ref":"86f9acae4a5d4803df0e1fd08f217046ce969911fb81c49342f61c1524a312eb","references":"","settled_by":"Path-integral molecular dynamics on a coupled-cluster-quality potential reproducing diffusion and isotope effect, with a committor or rate analysis of the transfer events.","status_note":"","title":"Rate-limiting step of proton transport in liquid water","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"f2319bf7f3396a14a247367fc786b0c7ff857c43557743b0f5ca556c93e464df","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"838eadd8e2d5292b22099ff165000891f3ae80fc424e49b5b5fcbe78cd049f18","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"ISCzXT95dQFaUASZQsyc0Dvo-OAXYAs1g-hHsb0yW1gvGo-lGgl7GXasY_1KoBC1sTH651ckMQWML8GTh3KSDA"},"schema":"pubphys.envelope/1"},"record_hash":"f2319bf7f3396a14a247367fc786b0c7ff857c43557743b0f5ca556c93e464df","leaf_index":2672}