Structural correlations in titanium dioxide

Molecular-dynamics simulations were performed, by using a phenomenological potential model, which takes into account steric repulsion due to atomic sizes, screened Coulomb interaction from charge transfer, charge-dipole interaction due to the large electronic polarizability of the anions, and dipole-dipole interaction, in order to investigate the short- and intermediate-order correlations in the amorphous phase of TiO₂. The results are presented for partial and total pair-distribution functions, coordination numbers, partial static structure factors, and density-density, charge-charge, and x-ray structure factors. Partial structure factors show that correlations at the length range 3-8 {} are responsible by the first sharp diffraction peak, which is almost absent in the charge-charge structure factor. Bond-angle distributions are also determined to analyze the orientational correlations in the various phases of the system. Our results are compared with experimental data inferred from x-ray spectroscopy.