The theoretical calculations of electron impact total ionization cross section for cycloalkane, aldehyde, and ketone group molecules are undertaken from ionization threshold to 2 keV. The present calculations are based on the spherical complex optical potential formalism and complex scattering potential ionization contribution method. The results of most of the targets studied compare fairly well with the recent measurements, wherever available and the cross sections for many targets are predicted for the first time. The correlation between the peak of ionization cross sections with number of target electrons and target parameters is also reported. It was found that the cross sections at their maximum depend linearly with the number of target electrons and with other target parameters, confirming the consistency of the values reported here.

Two independent methods, namely, Binary-encounter Bethe (BEB) and complex scattering potential-ionization contribution (CSP-ic) methods, are employed to calculate the total ionization cross section (Qion) for cyclic organic molecules from ionization threshold to 5 keV for which there is a paucity of data in the literature. The Qion calculated with the (BEB/ωB97X) combination is found to give good agreement with the experimental results, the CSP-ic method, and the Qion calculated from Irikura orbital energies. The Qion for most of the targets are calculated for the first time over such a wide energy range. Hence, to check the consistency and reliability of the present data, we have also computed the static polarizability for all the targets and the variation of maximum ionization cross section (Qion,max) with polarizability is studied. A linear relationship is observed between these quantities indicating the consistency and reliability of the present Qion data. The targets studied are important for industrial applications, radiation biology, and astrophysics.

In the present article we report a comprehensive calculation of total and differential cross sections for electron impact on allene (C${}_3$H${}_4$) molecule. The total cross sections are computed for a wide electron energy range from 0.1 eV to 2 keV. We have employed $R$-matrix code through quantemol-n software for ab initio calculations below 10 eV while intermediate- to high-energy calculations are performed using the spherical complex optical potential formalism. The two methods are found to be consistent at around 3 eV, merging smoothly. The results for both total and differential cross sections are in good agreement with previous results wherever available. We have also observed the presence of a shape resonance at 2.9 eV due to degenerate (${}^2$ $B_1$, ${}^2$ $B_2$) states. The electronic excitation cross section for $e$-C${}_3$H${}_4$ scattering is reported.