  We use first-principles density-functional calculations to determine the
frequency shift of the A$'_1$-${\bf K}$ phonon (Raman D band) in monolayer
graphene, as a function of the charge doping. A detailed DFT study on the
electron-phonon coupling and the phonon line width of E$_{2g}$-${\bm \Gamma}$
and A$'_1$-${\bf K}$ phonons are also performed for graphene multi-layers.
Furthermore, we explain the experimentally observed '1/(Number of Layers)'
behaviour of the Raman G band position after including the dynamic response
treated within time dependent perturbation theory.
