{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"330385c4e6261695dcaac49dff719f13d0058c5c93a1411a5f2139e82e6407e5","created":"2026-10-03T07:17:58Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"cb738cec3586c9cdbfb28b1c30a69c3ac8b5f568f0f3fc8ebf8af8ff505729e7","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":"1","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 $9.3e-5\\,\\mathrm{cm}^2/\\mathrm{s}$) and its H/D isotope effect and identifies the step from the trajectories.","problem_ref":null,"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":"8ba87b9cdffe8e8cf07699e738dbe5b7ba271aabae5cf5406a53e07fab8bdd45"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"86f9acae4a5d4803df0e1fd08f217046ce969911fb81c49342f61c1524a312eb","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"98dcc55afb4d54b2cdd37b2c8f99c39f471d7952b86695c1c845e083bd15bb32","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"GU0cLrKJnhvEDv9t0DUFEiN3yBzrb08dKIE33QJz4Ex0J1OH1-DFZzimMYzL0XtKKar3q97fyjOUnRzI1amuAQ"},"schema":"pubphys.envelope/1"},"record_hash":"86f9acae4a5d4803df0e1fd08f217046ce969911fb81c49342f61c1524a312eb","leaf_index":877}