Hydrodynamical simulations of coupled and uncoupled quintessence models
  I: Halo properties and the cosmic web
  We present the results of a series of adiabatic hydrodynamical simulations of
several quintessence models (both with a free and an interacting scalar field)
in comparison to a standard \LCDM\ cosmology. For each we use $2\times1024^3$
particles in a $250$\hMpc\ periodic box assuming WMAP7 cosmology. In this work
we focus on the properties of haloes in the cosmic web at $z=0$. The web is
classified into \emph{voids}, \emph{sheets}, \emph{filaments} and \emph{knots}
depending on the eigenvalues of the velocity shear tensor, which are an
excellent proxy for the underlying overdensity distribution. We find that the
properties of objects classified according to their surrounding environment
shows a substantial dependence on the underlying cosmology; for example, while
$V_{\rm max}$ shows average deviations of $\approx5$ per cent across the
different models when considering the full halo sample, comparing objects
classified according to their environment, the size of the deviation can be as
large as $20$ per cent.
  We also find that halo spin parameters are positively correlated to the
coupling, whereas halo concentrations show the opposite behaviour. Furthermore,
when studying the concentration-mass relation in different environments, we
find that in all cosmologies underdense regions have a larger normalization and
a shallower slope. While this behaviour is found to characterize all the
models, differences in the best-fit relations are enhanced in (coupled) dark
energy, thus providing a clearer prediction for this class of models.
