Hello, A change in allocation has been requested: Requester: ango (Anh Ngo) Project: AlN Title: A DFT study of reaction pathways of NH3 decomposition on AlN (0001) surface Description: Previously, we have performed structure optimizations of the adsorbate-free (0001) surface of AlN and determined reaction pathways for NH3 decomposition using (2 × 2) surface unit cells. Next, we will perform density functional theory (DFT) calculations to determine structure, bonding, and reaction energies of the Al adsorbed species. We will also extend our calculations to other surface orientations, including stepped surfaces. Periodic boundary condition (PBC) will be imposed in order to maintain periodicity of the solid support. Gradient corrected PBE density functional will be used for these calculations. The Climbing Nudged Elastic Band (cNEB) method of Henkelman and coworkers will be used to calculate transition states and activation barriers for formation of different surface species. Each structure in the supported (0001) surface of AlN typically involves ~100 atoms. To obtain accurate reaction energies and barriers, rigorous density functional theory (DFT) calculations are needed. We intend to carry out the DFT calculations using the VASP package. VASP is currently available on Blues cluster and scaling with number of processors is well established. For the MPI version of VASP with the system size of ~100 atoms, a good performance was observed up to 32 processors. Energy optimization in VASP takes approximately 1000 CPU hours and we plan approximately 200 of such calculations for different adsorbate geometries for each of 3 surface orientations. The Climbing Nudged Elastic Band (cNEB) calculation (with 5 to 7 images) takes approximately 3000 CPU hours and we plan to run 60 of these calculations to find reaction pathways. So our total request is 1000*200*3 + 60*3000 = 850,000 core hours Current: undetermined amount Justification: VASP performance on Blues is well established, we use the latest version maintained on Blues. Requested: 200000 A specific reason has been given: We need more allocation for this project. Thanks This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System