Crystal structure and hydroxyl group vibrational frequencies of phyllosilicates by DFT methods

A DFT study has been made for the 2 x 2 x 1 supercell of the crystal lattice of low-charge dioctahedral 2:1 phyllosilicates. Norm-conserving pseudopotentials of Al, Si, O, H, Na as well as the basis sets have been optimised. The generalized gradient approximation (GGA) was used with numerical atomic orbitals of the improved basis sets. Crystallographic and spectroscopical properties of some known samples with high charge have been calculated, being consistent with previous computational and experimental results. These results are useful to validate the pseudopotentials and basis set optimised to be applied to study the low-charge samples. Different low-charge dioctahedral 2:1 phyllosilicates have been calculated, revealing good agreement with experimental crystallographic properties. (C) 2009 Elsevier B.V. All rights reserved.