  A workflow is presented for performing pair distribution function (PDF)
analysis of defected materials using structures generated from atomistic
simulations. A large collection of structures, which differ in the types and
concentrations of defects present, are obtained through energy minimization
with an empirical interatomic potential. Each of the structures is refined
against an experimental PDF. The structures with the lowest goodness of fit
$R_w$ values are taken as being representative of the experimental structure.
The workflow is applied to anatase titanium dioxide ($a$-TiO$_2$) and
tetragonal zirconium dioxide ($t$-ZrO$_2$) synthesized in the presence of
microwave radiation, a low temperature process that generates disorder. The
results suggest that titanium vacancies and interstitials are the dominant
defects in $a$-TiO$_2$, while oxygen vacancies dominate in $t$-ZrO$_2$.
Analysis of the atomic displacement parameters extracted from the PDF
refinement and mean squared displacements calculated from molecular dynamics
simulations indicate that while these two quantities are closely related, it is
challenging to make quantitative comparisons between them. The workflow can be
applied to other materials systems, including nanoparticles.
