Time evolution of the σ₁ critical argument of the 3:2 resonance during the dissipation of the disk for the super-Earth case. The libration width grows with time and finally it turns into circulation (for both σ₁ and σ₂) when the density of the gas declines. This leads to the break up of the resonance and a period of chaotic evolution characterized by mutual close encounters. The initial value of Σ is equal to Σ_1MMSN.