Atomistic mechanism of proton conduction in solid CsHSO₄ by a first-principles study

The electronic structure and proton conduction mechanism of CsHSO ₄ in phases I and II have been studied by density-functional theory. The calculated results show that both phases have similar property in the electronic structure. Proton transfer paths and barriers have been investigated by the nudged elastic band method. The similarities and differences of proton transfers in two phases have been discussed. For phase I, the calculated results indicate that the reorientations of the sulfate tetrahedrons can take place frequently, which is in accordance with the experimental observation. For phase II, the highly ordered hydrogen-bond network makes the reorientation of the tetrahedron very difficult. The relatively disordered hydrogen-bond network in phase I plays an important role in the dynamics of tetrahedron, which speeds up proton transfer significantly. The atomistic proton-transfer mechanism in phase I is proposed.