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TY - CONF AU - Sitaraman, N. AU - Arias, T. AU - Farber, R.G. AU - Liepe, M. AU - Maniscalco, J.T. AU - Sibener, S.J. AU - Veit, R.D. ED - Michel, Peter ED - Arnold, André ED - Schaa, Volker RW TI - Ab Initio Calculations on Impurity Doped Niobium and Niobium Surfaces J2 - Proc. of SRF2019, Dresden, Germany, 30 June-05 July 2019 CY - Dresden, Germany T2 - International Conference on RF Superconductivity T3 - 19 LA - english AB - We develop and apply new tools to understand Nb surface chemistry and fundamental electronic processes using theoretical ab initio methods. We study the thermodynamics of impurities and hydrides in the near-surface region as well as their effect on the surface band gap. This makes it possible for experimentalists to relate changes in STM dI/dV measurements resulting from different preparations to changes in subsurface structure. We also calculate matrix elements for electron-impurity scattering in Nb for common impurities O, N, C, and H. By transforming these matrix elements into a Wannier function basis, we calculate lifetimes for a dense set of states on the Fermi surface and determine the mean free path as a function of impurity density. This technique can be generalized to calculate other scattering amplitudes and timescales relevant to SRF theory. PB - JACoW Publishing CP - Geneva, Switzerland SP - 523 EP - 526 KW - niobium KW - scattering KW - electron KW - experiment KW - lattice DA - 2019/08 PY - 2019 SN - 978-3-95450-211-0 DO - doi:10.18429/JACoW-SRF2019-TUP045 UR - http://jacow.org/srf2019/papers/tup045.pdf ER -