  We extend the resummation method of Anselmi & Pietroni (2012) to compute the
total density power spectrum in models of quintessence characterized by a
vanishing speed of sound. For standard $\Lambda$CDM cosmologies, this
resummation scheme allows predictions with an accuracy at the few percent level
beyond the range of scales where acoustic oscillations are present, therefore
comparable to other, common numerical tools. In addition, our theoretical
approach indicates an approximate but valuable and simple relation between the
power spectra for standard quintessence models and models where scalar field
perturbations appear at all scales. This, in turn, provides an educated guess
for the prediction of nonlinear growth in models with generic speed of sound,
particularly valuable since no numerical results are yet available.
