Theoretical Evaluation of Hydroxyapatite: The Effect of Structural Modification on Mechanical Properties

In this study, we explore the mechanical properties of the pure and strontium doped calcium hydroxyapatites by means of density functional theory computations. It has been demonstrated that strontium incorporation into hydroxyapatite can promote the solubility of apatite and osteocalcin levels as well. However, the influence of the structural modification on the mechanical characteristics must be identified before using them as biocompatible fillers in hybrid materials. Initially, the obtained structural parameters by geometry optimization are good consistent with the reported experimental values indicating accuracy of the calculations. Six independent elastic constants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio and elastic anisotropy are computed and compared in detail. The analysis of the elastic constants and other moduli discovers higher anisotropy on elasticity for the modified compound. Finally, the origins of these features which appear in various mechanical properties have been comprehensively discussed using density of states for these two materials.