An in silico Spectroscopic Study of the 45S5 Bioglass®

Among the standard solid-state experimental techniques, nuclear magnetic resonance (NMR), Raman and infrared spectroscopy are frequently employed to probe the structural features of different bioglasses compositions and to highlight the structural changes which characterize bioactivity. These techniques have revealed that the medium range order of the 45S5 Bioglass®1 is characterised by a very open silicate network dominated by Q2 and Q3 species even though the existence of more than two different Qn species of silicon and the presence of Si-O-P bonds for glasses with compositions similar to that of 45S5 glass is the subject of active debate. In this communication we will provide insights into the in silico NMR and IR spectra of the 45S5 Bioglass trying to shed lights into the final interpretation of the experimental spectra with respect to important structural features of this glass. The IR spectrum of the Bioglass® 45S5 has been simulated by means of periodic ab initio B3LYP calculations by means of the CRYSTAL06 code2 and Gaussian basis sets of double- quality.3 1D and 2D NMR spectra have been calculated by using the CASTEP code4, 5 with GGA-PBE6, 7 functional in conjunction with an home-made code based on the Floquet theory.8 1 L. L. Hench, R. J. Splinter, W. C. Alen, et al., J. Biomed. Mater. Res. 2, 117 (1971). 2 R. Dovesi, V. R. Saunders, C. Roetti, et al., edited by http://www.crystal.unito.it (University of Turin, Torino (Italy), 2006). 3 M. Corno, A. Pedone, R. Dovesi, et al., Chem Mater. 20, 56105621 (2008). 4 S. J. Clarck, M. D. Segall, C. J. Pickard, et al., Krystallogr. 220, 567 (2005). 5 C. J. Pickard and F. Mauri, Phys. Rev. B 63, 245101 (2001). 6 J. P. Perdew, K. Burke, and M. Ernzerhof, Phys. Rev. Letters 77, 3865 (1996). 7 J. P. Perdew, K. Burke, and M. Ernzerhof, Phys. Rev. Letters 78, 1396 (1997). 8 T. Charpentier, S. Ispas, M. Profeta, et al., J. Phys. Chem B 108, 4147 (2004).