Dissociative Electron Attachment to Polyatomic Systems

We have performed a multi-dimensional computational treatment of the dissociative electron attachment (DEA) dynamics of 3 polyatomic systems; HCCH, HCN/HNC and HCCCCN to investigate predicted inherent polyatomic effects. We have considered the following reaction channels: C$_2$H$_2$ (X$^1\Sigma_{g}^+$, $\nu$)+ e$^-$($E$) $\rightarrow$ (C$_2$H$_{2}$)$^{-*}$ ($^2\Pi_g$) $\rightarrow$ C$_2$H$^-$($^1\Sigma^+$,$\nu'$) + H($^2S$), HCN/HNC ($X^1\Sigma^+, \nu$) + e$^-$($E$) $\rightarrow$ (HCN/HNC)$^{-*}$ ($^2\Pi_g$) $\rightarrow$ CN$^-$($^1\Sigma, \nu'$) + H ($^2S$) and HCCCN (X$^1\Sigma^+$, $\nu$)+ e$^-$($E$) $\rightarrow$ HCCCN$^{-*}$ $\rightarrow$ $\left\{ \begin{array}{ll} $CCCN$^-(^2\Sigma^+ , \nu'^-_I) + $H$(^2S)$: (I)$ ; \\ $CN$^-(^1\Sigma^+ , \nu'^-_{II}) + $HCC$(^2\Sigma^+ , \nu'_{II})$: (II)$ ; \\ $HCC$^-(^1\Sigma^+ , \nu'^-_{III}) + $CN$ (^2\Sigma^+ , \nu'_{III})$: (III)$ ; \\ $CC$^-(^2\Sigma^+ , \nu'^-_{IV}) + $HCN$ (^1\Sigma^+ , \nu'_{IV}) $: (IV)$ ; \end{array} \right.$. We carried out electron scattering calculations using the Complex Kohn Variational Method with respect to a suitable internal coordinate system to obtain the complex resonant energy surfaces. We use this as input to a dynamics calculation using the Multiconfiguration Time-Dependant Hartree approach. We then compare our DEA cross sections and branching ratios to available experimental results.