Electronic structure, chemical bonding, and hyperfine parameters in layered silicates

The electronic structure of metal sites in 2:1 layer silicates was calculated employing the first-principles self-consistent discrete variational embedded cluster method, in the framework of density-functional theory. Densities of states, charge and spin densities, electric-field gradients, and magnetic fields were obtained for octahedral (Formula presented) sites in annite and compared with experimental measurements. The chemical environment for tetrahedral (Formula presented) sites ((Formula presented) and (Formula presented)) was also studied to determine atomic configurations and bonding structures. Cluster-size effects were investigated by systematically expanding the number of coordination shells included in the variational region.