Molecular simulation of ions substituted hydroxyapatite

Abstract

Hydroxyapatite (HA) structure has been of great interest in recent years, as it is present in bone and tooth. Through its application in the biomedical field, significantly in bone implants, performance of this structure became very important. As such, the incorporation of various ions, such as fluorine, into the HA structure had been extensively studied and investigated by some researchers.

This report would also unveil the process of modeling the hydroxyapatite and fluorapatite by the use of the Atomic Simulation Environment, package from the Python software. With the application of this program, the equivalent sites of the atoms in the structure can also be determined, thus enabling an accurate model of the various structures. The alignment problems faced in the modeling process would also be solved using geometrical calculations.

This project would carry out the investigation of the 50% incorporation of fluorine ions into the HA structure and also vary the location of this substituted fluorine ion at various sites. The long term stability of the structure would then be investigated through density functional theory methods. Through the results and investigation, it was concluded that the relative position of the fluorine ion with respect to the hydroxyl ion would affect the stability of the structure. In this project, the most stable configuration would be when both hydroxyl and fluorine ions lie on the same c-axis, residing at (0, 0, 0.75) and (0, 0, 0.25) respectively.