Conical intersections second-order degeneracy lifting

If the connection between the two surfaces is sloped, the funnel may well be more efficient. In addition, the degeneracy at a crossing point can also be lifted at second order. As a consequence, we can choose a coordinate system in which to mix the branching and intersection space coordinates to remove this splitting and preserve the degeneracy to second order. These new coordinates give the ciu-vature of the conical intersection hyperline and determine whether one has a minimum or a saddle point on it. These studies may also provide the vibrational modes that must be stimulated in order to enhance nonradiative decay because they decrease the energy gap and can lead to a Cl (see Paterson et al. 2004 Sicilia et al. 2007). 

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