Diabatic and adiabatic potential-energy surfaces for azomethane photochemistry

We propose an analytic form to represent the intersecting potential energy surfaces (PES) of the first two singlet states of azomethane. The aim is to run semiclassical simulations of photochemical events such as fragmentation and isomerization. The PES are based on ab initio calculations and corrected on the basis of available experimental data. We resort to a quasi-diabatic representation. suitable to deal with the So-SI conical intersection and to include the essential information about electronic couplings in a 2x2 effective hamiltonian matrix.