A theoretical study on orthosilicic acid dissociation in water clusters

The orthosilicic acid dissociation in water clusters has been studied within quantum chemical methods of Hartree–Fock, density functional theory with functionals В3LYP and M06-2X, and by means of the second order Møller–Plesset perturbance theory with 6-311++G(d,p) basis set. The thermodynamic and kinetic characteristics of proton transfer from orthosilicic acid molecule to water one have been calculated as well as the equilibrium constant (pKa) for this process. The dissociation constant values for the orthosilicic acid in water have been shown to be closest to the experimental data in case of DFT calculations involving the solvent effect (PCM).