Electron binding energies in linear dipole-bound (HCN)n− (n=2–5) anions

The (HCN)2− anion has been studied at the coupled cluster level of theory with single, double, and non-iterative triple excitations whereas equilibrium structures and electron binding energies for larger linear (HCN)n− (n=3–5) clusters have been determined at the second-order Møller–Plesset (MP2) level. The adiabatic electron affinity of (HCN)2 was found to be 399 cm−1 and trends in physically meaningful components of electron binding energy, such as static Coulomb, dispersion, and polarization stabilizations, were determined for this series of clusters. The 2Π dipole-bound anionic state was found for the pentamer with the MP2 vertical electron detachment energy of 92 cm−1.