Isotope effect in dissociative electron attachment to HCN

We performed nuclear dynamics calculations on HCN and DCN to study the isotope effect in dissociative electron attachment. Our previous calculations at 333 K led to a ratio {sigma}{sup (CN-/HCN)}/{sigma}{sup (CN-/DCN)} of about 13, which is significantly higher than recent experimental findings. This discrepancy is attributed to the neglect of correlation and polarization effects in the scattering calculation performed. We carried out a relaxed-self-consistent field calculation to determine the variation of the resonance parameters under these effects. We observe a shift in the positions of the shape resonance as well as a narrowing of the autoionization widths resulting in an isotope ratio of 3.2 at T=333 K; in closer agreement with the measured value.