Ab initio simulations of water and water ions

Ab initio studies of H⁺ and OH^- in water reveal a variety of interesting structures. In the case of the OH^-, an H ₉O₅^- structure is observed in which the four hydrogen bonds with the ligands lie in a plane that also contains the oxygen atom of the anion. In the case of H⁺, there is strong evidence for the existence of the H₉O₄⁺ structure originally postulated by Eigen and coworkers. Proton migration in this system is relatively fast and is observed to occur via the Grotthus mechanism.