Hartree-Fock study of pressure-induced strengthening of hydrogen bonding in lizardite-1T

The electron structures of lizardite were compared for two structural refinement at 0 and 1.25 GPa. The total energies of one hydrogen bond (HB) evaluated for the two structures are 29 and 43 kJ/mol, respectively. The strengthening frequency in IR spectra, and is characterized by means of difference electron density maps showing that the region of the HB is depleted of the electron density, and the degree of depletion indicates the strength of the HB. The maximum value of the 3D-2D depletion at 1.25 GPa is 0.020 e/bohr (super 3) , compared to 0.015 e/bohr (super 3) for the weaker HB at zero P. P-induced changes are documented with charge density maps, net atomic charges, overlap populations and partial density of states. The positions of the s bands are shown to be driven by the covalency/ionicity of the bonding, with increased ionicity causing the destabilization of energy levels.