Molecular statics calculations for iron oxide and oxyhydroxide minerals: Toward a flexible model of the reactive mineral-water interface

Journal Article · Wed May 01 04:00:00 EDT 1996 · Geochimica et Cosmochimica Acta

DOI:https://doi.org/10.1016/0016-7037(96)00046-4· OSTI ID:486301

Rustad, J R; Felmy, A R; Hay, B P ^[1]

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1. Pacific Northwest National Lab., Richland, WA (United States)

Molecular statics calculations are used to model the major FeOOH polymorphs and hematite. The potentials were taken from a previous investigation of Fe(III) in aqueous solutions which involved the extrapolation of the gas-phase Fe(III)-OH{sub 2} potential energy surface to the solvated hexaaqua complex. Using this model for the solid phases, lattice parameters for goethite, akaganeite, lepidocrocite, and hematite are generally within 4% of experiment. Internal energies (at 0 K) were computed for each structure; lepidocrocite is energetically the most stable polymorph, followed by akaganeite, with goethite being the least stable. While the model exhibits some variances with experiment, it performs remarkably well, despite the challenges constraint of being consistent with a dissociating molecular dynamics model for water in its gas, aqueous, and solid phases. Because of this consistency, the model allows qualitative theoretical treatment of previously unapproachable problems in mineral-water interface geochemistry. We apply the model to identify surface species on the solvated (110) surface of goethite. 29 refs., 5 figs., 3 tabs.

• DOE Contract Number: AC06-76RL01830
• OSTI ID: 486301
• Journal Information: Geochimica et Cosmochimica Acta, Journal Name: Geochimica et Cosmochimica Acta Journal Issue: 9 Vol. 60; ISSN 0016-7037; ISSN GCACAK
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
36 MATERIALS SCIENCE
54 ENVIRONMENTAL SCIENCES
CONTAINERS
CORROSION
GEOCHEMISTRY
GOETHITE
IRON OXIDES
MOLECULAR STRUCTURE
ROCK-FLUID INTERACTIONS
SOILS
SURFACE PROPERTIES