Dark Energy and Non-linear Perturbations
  Dark energy might have an influence on the formation of non--linear structures during the cosmic history. For example, in models in which dark energy couples to dark matter, it will be non--homogeneous and will influence the collapse of a dark matter overdensity. We use the spherical collapse model to estimate how much influence dark energy might have. 
C. van de Bruck and D.F. Mota