Hello, A change in allocation has been requested: Requester: dford (Denise Ford) Project: SRF-materials Title: Modeling of Impurity Structures in Niobium Superconducting Radio-Frequency Cavities Description: VASP will be used to perform density functional theory calculations of defective niobium and niobium oxide structures to assess the effects of impurities on the material. We will model the niobium oxides ranging from NbO - Nb2O5, including ideal structures and plausible defective structures, to determine the magnitude of magnetic impurities that the can be accommodated in the oxide surface layers. We will also model interstitial H, O, C, and N in niobium, with focus on the ability of C and N to trap H and prevent the formation of niobium hydride precipitates. We will also assess the electronic, magnetic, and structural properties of these impurities in niobium in consideration of the side-effects that they may have on SRF cavity performance. The models for these studies will involve several hundred atoms to accurately describe the structures and minimize undesired interactions between periodic images. The models for the oxide studies will require some parameter determination, such as selection of appropriate functionals, where as the models for the hydride studies have been previously established. Current: undetermined amount Justification: Requested: 200000 A specific reason has been given: More configurations of C in niobium need to be explored than originally anticipated. We would also like to calculate the phonon band structures and DOS using VASP. This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System