COLA with scale-dependent growth: applications to screened modified
  gravity models
  We present a general parallelized and easy-to-use code to perform numerical
simulations of structure formation using the COLA (COmoving Lagrangian
Acceleration) method for cosmological models that exhibit scale-dependent
growth at the level of first and second order Lagrangian perturbation theory.
For modified gravity theories we also include screening using a fast
approximate method that covers all the main examples of screening mechanisms in
the literature. We test the code by comparing it to full simulations of two
popular modified gravity models, namely $f(R)$ gravity and nDGP, and find good
agreement in the modified gravity boost-factors relative to $\Lambda$CDM even
when using a fairly small number of COLA time steps.
