Ab initio study of aqueous hydrochloric acid

Ab initio molecular dynamics simulations have been carried out for solutions of hydrochloric acid in water, under ambient conditions, over a wide range of concentrations. For acid-to-water mole ratios of 1:31 and 1:7 the hydrochloric acid molecules readily ionize to form hydrated chloride and hydronium ions. However, in a typical laboratory strength 1:3.6 solution, the textbook picture of separated solvated ions breaks down with the formation of a hydrogen-bonded species, Cl-H ... Cl-. The presence of this species should be observable in experiment and its detection and characterization could provide a stringent test of the current ab initio simulation methodology.