Ab initio modelling of complex systems with MPPcrystal

In this comunication the properties of amorphous silica, hydroxyapatite surfaces and the Hench's bioglass have been addressed by large scale B3LYP simulation. Amorphous silica is a key inorganic material with applications in many fields and it is the basic constituent of mesoporous ordered materials like MCM-41. Hydroxyapatite (HA, Ca10(PO4)6(OH)2) is the main constituent of the mineral phase in mammalian bones and teeth enamel and it is widely applied as an orthopaedic and dental biomaterial. The Hench Bioglass® 45S5 (46.1% SiO2, 26.9% CaO, 24.4% Na2O and 2.6% P2O5 molar composition) is of great interest in medical applications since in the presence of body fluids, it promotes the formation of a layer of biologically active bone-like hydroxyapatite at the implantation interface. In this seminar, realistic models of amorphous silica surfaces with different degree of hydroxylation and MCM-41 mesorporous material will be illustrated. As for hydroxyapatite and Hench Bioglass, the modeling of the interaction between a mini-protein (13 amino acids) with the most stable (001) surface of hydroxyapatite and the theoretical prediction of the vibrational spectrum of the Hench Bioglass 45S5 will also be discussed. For all these cases, a periodic approach based on the B3LYP functional and Gaussian-type basis functions will be adopted using the CRYSTAL09 code.