Car–Parrinello molecular dynamics in the DFT + U formalism: Structure and energetics of solvated ferrous and ferric ions

Journal Article · Sat Sep 01 04:00:00 EDT 2007 · Journal of Electroanalytical Chemistry, 607(1-2):107-112

DOI:https://doi.org/10.1016/j.jelechem.2007.01.008· OSTI ID:921406

Sit, P H L; Cococcioni, Matteo; Marzari, Nicola N

The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. We implemented a rotationally-invariant Hubbard U extension to density-functional theory in the Car–Parrinello molecular dynamics framework, with the goal of bringing the accuracy of the DFT + U approach to finite-temperature simulations, especially for liquids or solids containing transition-metal ions. First, we studied the effects on the Hubbard U on the static equilibrium structure of the hexaaqua ferrous and ferric ions, and the inner-sphere reorganization energy for the electron-transfer reaction between aqueous ferrous and ferric ions. It is found that the reorganization energy is increased, mostly as a result of the Fe–O distance elongation in the hexa-aqua ferrous ion. Second, we performed a first-principles molecular dynamics study of the solvation structure of the two aqueous ferrous and ferric ions. The Hubbard term is found to change the Fe–O radial distribution function for the ferrous ion, while having a negligible effect on the aqueous ferric ion. Moreover, the frequencies of vibrations between Fe and oxygen atoms in the first-solvation shell are shown to be unaffected by the Hubbard corrections for both ferrous and ferric ions.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 921406
• Journal Information: Journal of Electroanalytical Chemistry, 607(1-2):107-112, Journal Name: Journal of Electroanalytical Chemistry, 607(1-2):107-112 Journal Issue: 1-2 Vol. 607; ISSN JEACAX; ISSN 0368-1874
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CHEMICAL STATE
DENSITY FUNCTIONAL METHOD
ELECTRON TRANSFER
Environmental Molecular Sciences Laboratory
IRON COMPOUNDS
MOLECULAR DYNAMICS METHOD
MORPHOLOGY
SOLVATION