Dissociative electron attachment of polyatomic molecule at low collision energies: application to H$_2$CN

Dissociative electron attachment (DEA) of molecules is an important process in various plasma environment. Despite several approaches developed for diatomic molecules, the theoretical description of the DEA for polyatomic molecules is an extremely complex problem. Following the treatment proposed by Bardsley (1968) developed for diatomic molecules, we extend the formalism of resonant scattering to polyatomic molecules, assuming that there is no vibrational excitation. We applied our method to the H$_2$CN molecule, which has six normal modes and is responsible for the formation of the CN$^-$ and H$^-$ ions and the HCN molecule in the interstellar space. Positions and widths of the resonances responsible for DEA process are computed using the UK R-matrix code. The partial width for the electron capture is obtained from the time-delay matrix. With the new model, the total DEA cross section for H$_2$CN molecule is computed.