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: This phase of the project will focus on surface and interface properties. We are particularly interested in the change in superconducting properties at surfaces and across the interfaces between the host niobium and impurity phase precipitates. Since the lattices of the precipitates and the host niobium metal may deform considerably near the interfaces, we will consider bulk models of precipitates and the niobium under strain, as well as full interface models. The models will consist of up ~100 atoms. Density functional theory in VASP will be used to optimize the geometries of the models and calculate their electronic properties. Phonon DOS and dispersions will be evaluated using Phonopy, which uses the force constants calculated for atomic perturbations via density functional theory in VASP. Since defects, including interfaces, reduce the symmetry of the systems, many perturbations will need to be performed for some of these models to accurately assess the phonon properties. Abinit will also be used to calculate the superconducting properties (electron-phonon coupling and transition temperature) of select structures. Accurate determination of the electron-phonon coupling is very computationally demanding, requiring dense k-point and q-point grids. Abinit parallelizes over k-points, bands, and perturbations; so it is particularly suitable for use on large machines with many cores. Current: undetermined amount Justification: Requested: 150000 A specific reason has been given: I need to complete a few more DFPT calculations with Abinit, which works very well on Blues. The extra time will be very helpful to this project. This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System