Hydrogen bond connectivity in jennite from ab initio simulations

The protonation scheme and the hydrogen bond connectivity in the structure of jennite were investigated by ab initio molecular dynamics simulations. The calculated statistics of hydrogen bonds at ambient conditions is consistent with the protonation scheme proposed by Bonaccorsi et al. (2004) based on the bond valence theory. The protons in the system are associated with the 2Ca-OH linkage and H2O molecules. The dangling Si-O bond on the bridging tetrahedra is de-protonated. The proton dynamics revealed in the molecular dynamic simulations explains the apparent discrepancies in the NMR and X-ray diffraction studies of jennite. (C) 2008 Elsevier Ltd. All rights reserved.