The simulation without coupling between G and K phonons (Γph−ph = 0) is equivalent to the 2T model. It always gives a curve that is shifted from the Raman data to earlier times (Fig. 1(a)) because the 2T model predicts that the G-phonons are generated starting at t ~ −35 fs due to the finite width of the pulse. Note that the coupling constant λG in Γe−ph only determines the time constant of the G-phonon generation, but it has no influence on when TG starts to rise. As a result, the phonon dynamics in the early stage of relaxation is clearly not consistent with the 2T model.