Acceleration correction to the binary-encounter Bethe model for the electron-impact ionization of molecules

We propose a generalized binary-encounter Bethe model (GBEB) based on corrected acceleration energies to predict the electron-impact ionization cross sections of molecules. The acceleration energy of the incident electron is inversely proportional to the molecular effective charge felt by the ejected electron. The symmetry of molecular orbitals is analyzed to determine the core and valence effective charges. We tested the GBEB model on several organic, inorganic, and atmospheric molecules with increasing complexity. The calculated total ionization cross sections are in better agreement with the experimental data than the predictions from the original BEB model. Another major advantage of the present model rests upon the convenience that it does not need any ad hoc correction used in previous BEB models.