Abstract
We investigated elastic collisions of low-energy electrons with the hydrogen-bonded formic-acid dimer, formamide dimer, and formic-acid–formamide complex. We focused on how the shape resonances of the isolated monomers are affected when bonded to another molecule. The scattering cross sections were computed with the Schwinger multichannel method with pseudopotentials in the static-exchange and static-exchange-plus-polarization approximations, for energies ranging from 1 to 6 eV. The present results support the existence of two low-lying shape resonances for the formic-acid dimer, as suggested in previous theoretical and experimental studies. We also found low-lying shape resonances for the formamide dimer and for the formic-acid–formamide complex. For the dimers, the presence of a center of inversion is key to understanding how these resonances arise from linear combinations of the anion states of the respective monomers. For the formic-acid–formamide complex, the resonances are more localized on each unit, lying at lower energies with respect to the isolated monomers. The present results suggest that if there is no delocalization of the resonances over the pair for hydrogen-bonded molecules, then their positions would lie below those of the units.
- Received 18 October 2011
DOI:https://doi.org/10.1103/PhysRevA.84.062714
©2011 American Physical Society