  Dopant impurity potentials determined by ab-initio supercell DFT calculations
are used to calculate the optical conductivity of overdoped LSCO and Tl-2201 in
the superconducting and normal states. Vertex corrections are included, to
account for the effect of forward scattering on two-particle properties. This
approach was previously shown to provide good, semiquantitative agreement with
measurements of superfluid density in LSCO. Here we compare calculations of
conductivity with measurements of THz conductivity on LSCO using identical
impurity, band, and correlation parameters, and find similarly good
correspondence with experiment. In the process, we delineate the impact of the
different disorder mechanisms on single-particle and transport relaxation
processes. In particular, we reveal the critical role of apical oxygen
vacancies in transport scattering and show that transport relaxation rates in
LSCO are significantly reduced when apical oxygen vacancies are annealed out.
These considerations are shown to be crucial for understanding the variability
of experimental results on overdoped LSCO in samples of nominally identical
doping but different types. Finally, we give predictions for Tl-2201 THz
conductivity experiments.
