Ab Initio study of Ferrihydrite and related Iron-oxyhydroxide polymorphs:

bulk and surface structural modeling, adsorption modeling

Nathan Pinney, Dane Morgan, Materials Science Program

Ferrihydrite is a relatively common mineral found ubiquitously in nature and is of importance as an industrial and environmental sorbent.  Due to small grain nanocrystallinity of ferrihydrite (2-7nm diameter particles), the equilibrium structure of the material has been difficult to characterize from conventional experiments that rely on long-range order.  A research collaboration has been formed to utilize new experimental and theoretical techniques to better understand ferrihydrite and its formation and adsorption properties and includes members from Stony Brook University (NY), the University of Wisconsin-Madison, Temple University and Penn State University,

We will use ab initio methods, via VASP, to confirm initial structural data from Stony Brook University x-ray scattering experiments and pair-distribution function (PDF) analysis.  Relative energies/stabilities between ferrihydrite and related iron oxyhydroxides (goethite, lepidocrocite) and oxides (hematite) are of immediate interest, progressing to surface structural modeling and investigation of adsorption phenomena as a function of surface binding sites, nanoparticle size dependence etc.

We gratefully acknowledge financial support from the National Science Foundation (NSF), Chemistry (CHE) division, award number 0714183.