title: Near-Quantitative Agreement of Model-Free DFT-MD Predictions with XAFS Observations of the Hydration Structure of Highly Charged Transition-Metal Ions.
abstract: First-principles dynamics simulations (DFT, PBE96, and PBE0) and electron scattering calculations (FEFF9) provide near-quantitative agreement with new and existing XAFS measurements for a series of transition-metal ions interacting with their hydration shells via complex mechanisms (high spin, covalency, charge transfer, etc.). This analysis does not require either the development of empirical interparticle interaction potentials or structural models of hydration. However, it provides consistent parameter-free analysis and improved agreement with the higher-R scattering region (first- and second-shell structure, symmetry, dynamic disorder, and multiple scattering) for this comprehensive series of ions. DFT+GGA MD methods provide a high level of agreement. However, improvements are observed when exact exchange is included. Higher accuracy in the pseudopotential description of the atomic potential, including core polarization and reducing core radii, was necessary for very detailed agreement. The first-principles nature of this approach supports its application to more complex systems.
authors: †Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States.
authors: John L
authors: JL
authors: Fulton
authors: †Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States.
authors: Eric J
authors: EJ
authors: Bylaska
authors: §Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States.
authors: Stuart
authors: S
authors: Bogatko
authors: ‡Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States.
authors: Mahalingam
authors: M
authors: Balasubramanian
authors: §Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States.
authors: Emilie
authors: E
authors: Cauët
authors: †Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States.
authors: Gregory K
authors: GK
authors: Schenter
authors: §Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States.
authors: John H
authors: JH
authors: Weare
keywords: DFT; XAFS; aqueous; ions; simulation; transition metals