Effect of Chlorination on the Shape Resonance Spectrum of CHBr and CClBr Molecules in Collisions with Electrons.

In this work, we present a theoretical study of elastic electron scattering by the CHBr and CClBr molecules using the Schwinger multichannel method. Through the scattering amplitudes computed at the static-exchange and static-exchange plus polarization levels of approximation, we have obtained integral, momentum transfer, and differential cross sections for energies ranging from 0 to 20 eV. For both systems, the resonance spectrum was identified in the cross sections and characterized with basis on the analysis of the eigenvalues and eigenvectors obtained by diagonalization of the scattering Hamiltonian.

Elastic and Electronically Inelastic Cross Sections for the Scattering of Electrons by Pyrrole.

Integral and differential cross sections for elastic and electronically inelastic electron scattering from the pyrrole molecule are reported. The cross section calculations employed the Schwinger multichannel method with norm-conserving pseudopotentials. The collision dynamics was described according to a model in which up to 209 energetically accessible channels were treated as open.

Elastic and electronically inelastic scattering of electrons by the pyrazine molecule.

We report on elastic and electronically inelastic integral and differential cross sections as well as ionization and total cross sections for electron collisions with the pyrazine molecule. The Schwinger multichannel method is applied in calculations carried out according to the minimal orbital basis for single configuration interactions strategy from the 1-channel up to 139-channels close-coupling level of approximation. With these calculations we have obtained integral and differential cross sections as well as excitation functions for elastic electron scattering and, also, integral and differential cross sections for electronic excitation from the ground state to the B, B, B, B, B and B excited states of pyrazine by electron impact.

Elastic Electron Scattering by Diborane(6) and Diborane(4) Molecules.

We present integral, differential, and momentum transfer cross sections for elastic electron collisions with the two most stable isomers of the BH molecule, hereafter referred to as isomer I ( symmetry) and isomer II ( symmetry), and with the BH molecule ( symmetry). The isomer I of BH and the BH molecule are known for their electrodeficiency in the "three-center two-electron" (3c-2e) bond, a region in which a hydrogen atom occupies a bridged position between two non-hydrogen atoms. The cross sections were computed by using the Schwinger multichannel method implemented with norm-conserving pseudopotentials, and the scattering calculations were carried out in the static-exchange and static-exchange plus polarization levels of approximation for energies from 0.

Electron and Positron Scattering by the Formamide Molecule.

We report calculated elastic integral, differential, and momentum transfer cross sections for electron and positron collisions with the formamide (HCONH) molecule, for impact energies up to 10 eV. We have used the Schwinger multichannel method in the static-exchange and static-exchange plus polarization approximation for collisions of electrons and the static plus polarization approximation for collisions of positrons. The Born-closure procedure was applied to account for the long-range potential due to the permanent dipole moment of formamide.