Ab initio density functional theory applied to the structure and proton dynamics of clays

Ab initio molecular dynamics and total energy calculations are combined to determine the orientation of hydroxyl groups and to localize the components of the vibrational spectra of dickite. The inner hydroxyl and one inner-surface hydroxyl form a horizontally oriented pair producing high-frequency components in the region of the O–H stretching. Other two hydroxyls make interlayer contacts and produce two down-shifted stretching bands.