ExperimIn the light of these experi

ExperimIn the light of these experimental observations, in order to reveal the mechanism of CSP, we focused our modeling efforts on investigating the impact of acid concentration on interfacial kinetics at the atomistic level. We conducted molecular dynamics (MD) simulations using the reactive force field (ReaxFF) potential[8]. The ReaxFF is an MD procedure that is capable of modeling reactive liquid/solid interfaces at elevated temperatures and pressures. The ReaxFF force field parameters are optimized to reproduce the energetics of reference reaction events which were obtained by using more accurate methods such as density functional theory. Note that ReaxFF may not reproduce reaction events that are not included in the parameter optimization process with same accuracy as reference reactions;[9] therefore, ReaxFF should be applied deliberately. The force field used in this study has been used in several different studies with similar chemistry and successfully reproduced relevant experimental results.[10] Systems in computational simulations were prepared to mimic experimental conditions by using the same acid concentrations. The initial atomistic system was prepared to represent the beginning of the final stage of CSP at which the system was assumed to be at thermodynamic equilibrium; thus, there is no chemical potential difference between the pore and the GB region (i.e., the dissolved material concentrations in the GB and the pore fluid are assumed to be equal and constant).Thereby, the simulation boxes involved the ZnO surface and solvent molecules (water, HAc) saturated with a fixed number of dissolved Zn+2 ions. For details of the computational studies, see the Supporting Information. In order to decrease the liquid content, the systems were slowly heated up to the temperatures at which recrystallization starts.