Clustering GCG: a viable option for unified dark matter-dark energy?
  We study the clustering Generalized Chaplygin Gas (GCG) as a possible
candidate for dark matter-dark energy unification. The vanishing speed of sound
($c_{s}^2 = 0$) for the GCG fluid can be obtained by incorporating higher
derivative operator in the original K-essence Lagrangian. The evolution of the
density fluctuations in the GCG+Baryon fluid is studied in the linear regime.
The observational constraints on the model are obtained using latest data from
SNIa, $H(z)$, BAO and also for the $f\sigma_{8}$ measurements. The matter power
spectra for the allowed parameter values are well behaved without any
unphysical features.
