Hello, A change in allocation has been requested: Requester: rhadt (Ryan Hadt) Project: HER_OER Title: Geometric and electronic structure contributions to oxygen and hydrogen evolution reactions Description: Our focus is currently on understanding the geometric and electronic structure contributions to the formation of low- and high-valent intermediates involved in the HER or OER. In the former, this typically involves the protonation of highly reduced metal centers to form metal-hydride species. The metal-hydride species can be protonated again to evolve hydrogen. However, the mechanism of H-H bond formation is not well defined, and can involve homolytic or heterolytic pathways. In OER, high-valent metal-oxo species can react through radical coupling, H-atom abstraction from water, or nucleophilic attack. We will therefore focus on better understanding the geometric and electronic structures of the low- and high-valent precursors as well as catalytically active species and how these contribute to the various mechanisms of H-H and O-O bond formation. Our research also involves the direct spectroscopic characterization of the precusors to the catalytically active. T hus, these calculations can be directly correlated and compared to experimental data. The specific calculations will be carried out as follows. We will run gas-phase DFT geometry optimizations on all key species involved in catalytic cycles. Frequency and wave function stability checks will be required for all geometries. Single point calculations will be carried out to determine DFT energies at the basis set limit. This will allow for the calculation of redox potentials and pKas. Additional single point calculations (including time-dependent DFT) will be carried out to directly correlate the electronic structure to experimental data (e.g., UV-vis, electron paramagnetic resonance (EPR), X-ray absorption and emission (XAS/XES)). Lastly, potential energy surfaces (PESs) will be carried out to directly monitor electronic structure evolution during bond-forming and bond-breaking reactions. PES generation will involve a series of constrained geometry optimizations around the transition state, and thus requires the same calculations as indicated above for ground state species. All geometry optimizations, frequency calculations, and stability checks will be carried out in Gaussian09 (G09). Single point energy calculations will also be carried out using G09. Orca 3.0.3 is an imperative program for the calculation of UV-vis, EPR, XAS, and XES parameters for direct comparison to our experimental data. Our experience indicates that ~40,000 CPU hours are necessary for geometry optimizations of ground states and PESs, ~20,000 CPU hours are necessary for frequency calculations and transition state searches, ~10,000 CPU hours are necessary of stability checks, and ~30,000 CPU hours are necessary for additional single point energy and properties calculations. Thus, we request 100,000 CPU hours. Current: undetermined amount Justification: Requested: 20000 A specific reason has been given: Additional computational projects beyond those originally proposed have come up. Note these projects are also under the main scope of the proposal. This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System