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 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 integral cross section 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

In the present article we have proposed and tested a new polarization scheme within the Schwinger Multichannel method based on a model potential to describe positron-molecule polarization and correlation. For this test, we have calculated integral and differential cross sections for the elastic scattering of positrons by pyrazine and compared these results with the existing theoretical and experimental data. Furthermore, in order to evaluate the possible bound state, we have also obtained the scattering lenghts. Our current results greatly improved previous {\it ab-initio} calculations showing a significantly better agreement between the theoretical results and experimental results, particularly at low angles for the differential cross sections.

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