Francisco Fernandes Frighetto

We employed our recent version of the Schwinger multichannel method, implemented with a model potential [F. F. Frighetto, A. S. Barbosa, and S. d'A. Sanchez, Phys. Rev. A 108, 012818 (2023)] to calculate cross sections for elastic positron scattering by a set of hydrocarbons. Initially, by comparing the model potential calculations for methane, ethylene, and acetylene with our best possible ab initio calculations to date, we obtained the cutoff parameter for the carbon atom. Our results show that this parameter depends on the hybridization of the carbon atom for each molecule. We then applied the same cutoff parameter for the model potential to calculate the cross sections for other saturated and unsaturated hydrocarbons with encouraging results. We also discuss the positron binding to these hydrocarbons and compare the present results with available data from the literature.

In the present work we report elastic cross sections for electron scattering from acrylic acid (CH₂ = CH-COOH) and its methylated derivatives, crotonic acid (CH₃-CH = CH-COOH), methacrylic acid (H₂C = C(CH₃)COOH) and methyl acrylate (CH₂ = CHCOOCH₃). The calculations were performed with the Schwinger multichannel method for impact energies up to 15 eV. Two π* shape resonances were found in the component of the integral cross sections (ICSs) for the A″ symmetry of all molecules. The resonance positions obtained for the acrylic acid are compared with existing experimental results for dissociative electron attachment. We investigated the influence of methylation through the comparison of the positions and widths of the shape resonances in the component of the ICS of the A″, and the oscillation patterns in the differential cross sections of all molecules. We also present the momentum transfer cross section for electron scattering from all molecules studied.