Hydrxyapatite surface optimization by DFT calculations

G. DODERO; A. DIAZ COMPAÑY; A. JUAN; S. SIMONETTI

Conferencia; 2nd International Conference MATERIAL SCIENCE & NANOTECHNOLOGY; 2019

The development of modern theoretical surface science provides an opportunity to investigate structures on the atomic scale with useful applications in industrial technologies. Due to their high surface areas and pore volumes, hydroxyapatite attracts great attention in novel biomedical applications. Calculations reported in this work were performed in the framework of the Density Functional Theory (DFT) using the Vienna Ab-initio Simulation Package. In this code plane wave basis sets are used to solve the Kohn-Sham equations. The electron projector augmented wave (PAW) method was used and the generalized gradient approximation (GGA) with the Perdew?Burke?Ernzerhof (PBE) functional was utilized. The fixed convergence of the plane-wave expansion was found with cut-off energy of 400 eV. A set of 3×3×1 Monkhorst-Pack k-points was used to sample the Brillouin Zone. The ground state was found by a Methfessel-Paxton smearing of 0.2eV. The surface was represented with a periodically repeated slab containing 88 atoms (O:52, H:4, P:12, Ca:20) separated in the normal direction by a vacuum region. The width of this gap was optimized to avoid the interaction between slabs. The result is a surface model whose morphology and energy is in a good agreement with the experimentally measured values for hydroxyapatite surface.