Electron-defect interactions and low temperature carrier mobility from first principles

Electron-defect (e-d) interactions control charge and spin transport at low temperature and induce well-known conductance fluctuation and weak localization effects. While established ab initio methods and code exist for treating electron-phonon (e-ph) interactions, ab initio e-d calculations are still in their infancy, mainly due to the formidable computational cost of computing e-d matrix elements and self-energies from calculations on supercells containing the defect. In this talk, we formulate an efficient approach for computing e-d matrix elements using mainly unit cell quantities, and demonstrate its numerical implementation in the PERTURBO code. Using this approach, we can compute and systematically converge the e-d scattering rates for neutral defects such as vacancy and interstitial atom in silicon, and obtain the corresponding defect-limited low temperature mobility. The results deviate in important ways from broadly used empirical approaches to treat e-d interactions, highlighting the shortcomings of these simple models. Efforts on interpolating e-d matrix elements, computing higher-order e-d processes, and releasing the e-d routines in PERTURBO will be discussed.