English: Graphical representation of the variation of energy as a function of a spacial coordinate z (which may be varying in time) around an avoided crossing. The dashed lines represent the energy of the diabatic states (which cross each other at z_c) and the full lines represent the energy of the adiabatic states (eigenvalues of the Hamiltonian) which do not cross, appearing to avoid each other. In the illustrated case the eigenvalues trace the shape of a hyperbola to which the diabatic states energy are the asymptotes. This is the case for which the Landau-Zener equation was derived.