Quantum mechanical calculations on FeOH nanoparticles

Density functional theory calculations were performed on FeOH nanoparticles based on the goethite and a proposed ferrihydrite structures. Both molecular cluster and a periodic boundary condition approaches were applied and the resulting structures compared to the bulk values and to the other computational method. Reaction energies for Al3 +-substitution into each nanoparticle were calculated. The implications of these results for ferrihydrite and goethite nucleation and the ferrihydrite to goethite phase transition are discussed.

► DFT calculations on ferrihydrite and goethite nanoparticles were conducted.
► Proposed structure of Michel et al. (2007) is metastable as a nanoparticle.
► Al(III)-substitution into ferrihydrite is less stable than into goethite.
► Al(III) slows the ferrihydrite-to-goethite phase transition due to diffusion.