Abstract
OsO4 and RuO4 are molecular oxides with unique tetrameric structures and rare +8 oxidation states. Accurately modeling their properties remains challenging for density functional theory (DFT) due to weak intertetramer interactions, which standard functionals fail to capture. Here, we show that the van der Waals (vdW)-corrected density functional (vdW-DF-optB86b) provides structural parameters that are much closer to experimental values than the standard generalized gradient approximation, with volume predictions that fall within the experimentally observed range. Phonon band structure analysis shows that the inclusion of vdW interactions stabilizes soft phonon modes, highlighting the importance of dispersion corrections for accurate predictions of lattice dynamics. Experimental measurements of the phonon density of states for OsO4, obtained via inelastic neutron scattering, demonstrate good agreement with our vdW-DF-optB86b calculations. These results validate OsO4 and RuO4 as valuable benchmarks for structural and vibrational calculations via vdW-corrected DFT methods and offer insights for studying the broader class of sparse molecular materials.
| Original language | English |
|---|---|
| Pages (from-to) | 7450-7455 |
| Number of pages | 6 |
| Journal | Journal of Physical Chemistry C |
| Volume | 129 |
| Issue number | 15 |
| DOIs | |
| State | Published - Apr 17 2025 |
Funding
Andrew May, Michael McGuire, Blake Henry, April Case, Susan Fiscor, Allison Fortner, Tom Mooney, Ahmad Mitoubsi, and Alex Koldys are acknowledged for assistance in the preparation and execution of the safety procedures for handling the osmium tetroxide sample, as well as its disposal. This research was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. The calculations used resources of the Compute and Data Environment for Science (CADES) at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725 and resources of the National Energy Research Scientific Computing Center (NERSC), a Department of Energy Office of Science User Facility using NERSC award BES-ERCAP-m1057. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. Beamtime was allocated on proposals IPTS-33575 and IPTS-33765 at VISION and ARCS, respectively.