The compressional behaviour and the mechanical properties of talc [Mg3Si4O10(OH)2]: A density functional theory investigation

In this work, we modelled the structure, the compressional behaviour and the physical properties of talc over a wide range of pressure using a quantum mechanical approach based on periodic boundary conditions. We adopted the density functional theory using the B3LYP-D* functional, which includes a correction for the dispersive forces and all-electron Gaussian-type orbitals basis sets. An atomic level description of the athermal pressure-induced structural modification of talc is provided. From the compression results, we obtained the athermal (T = 0 K) bulk modulus (KT0), its first derivative (K′) and the athermal volume at zero pressure (V0) by a third-order Birch-Murnaghan equation with parameters KT0= 56.25 GPa, K′ = 5.66 and V0= 450.34 Å3. The mechanical behaviour is highly anisotropic, as observed by the axial compressibility. The presented data are in very good agreement with recent experimental results obtained by single-crystal neutron and X-ray diffraction experiments. © 2014 Springer-Verlag Berlin Heidelberg