English: The Wigner function time-evolution of the Morse potential: ${\displaystyle U(x)=20(1-e^{-0.16x})^{2}}$ in atomic units (a.u.). The solid lines represent the level set of the Hamiltonian ${\displaystyle H(x,p)=p^{2}/2+U(x)}$. The Wigner function for the first excited state of a harmonic oscillator is chosen as the initial condition. The Wigner's function normalization is ${\displaystyle \int dxdp\,|W(x,p)|^{2}=1}$ during the entire evolution.