Ab-initio total energy study of uncharged 2:1 clays and their interaction with water

Ab-initio total energy pseudopotential calculations were performed on talc and pyrophyllite to assess the success of the method in determining the structure of layered silicates. The calculated relative atomic coordinates were in good agreement with experiment. Further calculations were undertaken to determine the probable position of water in hydrated 10 A talc. It was found that the water molecule does not react with the clay's hydroxyl group to form H3O+, as has previously been suggested. Instead it is loosely bound midway between the talc layers, with its oxygen lying above the hydroxyl group. No equivalent hydrated phase was found for pyrophyllite.