Hello, A change in allocation has been requested: Requester: walkosz (Weronika Walkosz) Project: Metastable_Materials Title: First-principles studies of growth mechanisms for metastable materials Description: We will perform first-principles calculations for the adsorption and diffusion of NH3 on GaN, InN, and In surfaces through reaction intermediates such as NH2, NH, N, and H. The simulations will be performed with Vienna Ab-initio Simulation Package (VASP), using plane wave basis sets and PAW potentials. We will first model surfaces of GaN, InN, and In metal in the presence of NH3 to determine the most stable surface sites/configurations for the absorbed NH3 and its decomposed species. Next, diffusion and dissociation pathways of NH3 on various surfaces will be studied by calculating energy barriers using the Nudged Elastic Band Method. The scale of the proposed calculations exceeds small computer cluster capacity. Therefore, we are requesting the LCRC resources to perform a computational study of NH3 on GaN, InN, and In metal. The speed and reliability of the Fusion cluster will allow us to finish the work in a timely manner. The calculations of adsorption a nd decomposition of NH3 on different surfaces will take approximately 48 hours each when ran on 64 processors. At least 50 different structures will be calculated. The calculations of the reaction energy barriers (NEB), on the other hand, will require about 96 hours each when ran on 80 processors as determined by on our previous experience with these types of calculations on semiconductors. At least 42 reaction barriers need to be calculated to validate a diffusion model. Therefore, a total allocation of ~ 475,000 processor hours will be needed to perform the proposed calculations. Current: undetermined amount Justification: Requested: 300000 A specific reason has been given: I ran out of units. I am in the middle of my project (which involves a collaboration with the experimental group) and it is crucial that I run jobs systematically and not fall behind the work. This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System