Ab initio calculations of low-energy electron scattering by HCN molecules: Dependence on internuclear distance in linear geometry
Abstract
Low-energy electron scattering with HCN molecules is studied in the SEP (static-exchange plus parameter-free polarization potential) model as a function of both bond (CH and CN) stretches. A 2Π resonance at the equilibrium geometry behaves very similarly to the CO 2Π resonance as the CN bond is stretched; the corresponding HCN-(2Π) potential surface seems to cross the neutral curve (HCN, 1Σ+) around 2.9 a.u. of CN distance. In 2Σ symmetry, where no shape resonance is present at equilibrium geometry, a broad resonance appears when the CH or CN bonds are stretched well beyond the equilibrium position; the former appears to cross the 1Σ+ curve at about 2.8 a.u., i.e., just below the H+CN- asymptote, the latter to approach the neutral curve much more slowly and tangentially. Structure interpreted as a Π resonance in vibrational excitation, and as necessarily of Σ character in dissociative attachment to the lowest anion-neutral asymptote, can be explained as due to the mixing of the lowest linear 2Π and 2Σ resonances through bending (the Renner-Teller effect) and the peculiarity (cusp behavior) associated with anion-neutral curve crossings in polar molecules.
- Publication:
-
Journal of Chemical Physics
- Pub Date:
- January 1986
- DOI:
- 10.1063/1.450570
- Bibcode:
- 1986JChPh..84..739J
- Keywords:
-
- Electron Energy;
- Electron Scattering;
- Hydrocyanic Acid;
- Internuclear Properties;
- Molecular Oscillations;
- Vibrational Spectra;
- Hartree-Fock-Slater Method;
- Potential Energy;
- Atomic and Molecular Physics