Cross section calculations for resonance-dominated photodissociation of HCN via the excited Ã1A″ electronic state

The multi-reference internally contracted configuration interaction (MRCI) method is used to generate the potential energy functions (PEF) of the ground X 1Σ+ and excited à 1A″ electronic states of HCN molecule, as well as the corresponding transition dipole moment function. The resonance dominated photodissociation cross section is calculated using a filter diagonalization method to determine the complex eigenvalues of the final quasi-bound states as well as the complex transition dipole matrix elements. An alternative iterative method, based on the recursive polynomial expansion of the absorbing-boundary conditions Green operator, was also tested in cross section calculations. All nonadiabatic effects are neglected and molecular rotations are ignored.