Researches the influence of isomorphic cation substitution and pressure on the crystal structure, link geometry and atomic groups, and the properties and reactivity of phyllosilicates, particularly 2:1 dioctahedral phyllosilicates. Special emphasis is placed on five aspects: i) compositional; ii) cation order/disorder; iii) elastic properties; iv) dehydroxylation reaction mechanisms; v) adsorption. All this research is carried out by means of quantum mechanical calculations within the density functional theory using high-speed computers and IT facilities