Elastic and rotational excitation cross sections for electron scattering by polyatomic molecules

R-matrix calculations of low-energy electron alkane collisions

“…The results with the higher threshold show the undulations characteristic of an incomplete basis. Figure 12 compares our momentum transfer cross section with the experimental results of Tanaka et al (1982), and the theoretical results of Machado et al (2002). Both the present work, and Machado et al (2002) show reasonable agreement with the experimental values recommended by Song et al (2014), although in both cases the peak is shifted to higher energy.…”

“…This problem will be used as test case for these codes. In this context it is interesting to note that Machado et al (2002), who find significantly higher cross sections at low angles than us and hence better agreement with experiment, use ℓ up to 16 in their calculations.…”

“…Otherwise we obtain good agreement with the measured cross sections and in particular they agree with the recommendations of Song et al (2014), which were compiled from consideration of multiple experiment results, at all energies. Nestmann et al (1994), as well as the Schwinger variational iterative method calculations by Machado et al (2002). The recommended values of Song et al (2014) are also given.…”

“…However it is well-established that close-coupling based methods have difficulty converging the polarization potential (Gil et al 1994, Varambhia et al 2008. Theoretical treatments have considered elastic scattering (Boesten and Tanaka 1991, Jain and Baluja 1992, Machado et al 2002, as well as electron impact rotational (Jain and Thompson 1983, Brescansin et al 1989, Machado et al 2002, vibrational (Althorpe et al 1995(Althorpe et al , Čurík et al 2008 and electronic excitation (Gil et al 1994, Bettega et al 1998, Winstead et al 1993, Kato et al 2009. Recently Ziółlkowski et al (2012) used a closecoupling R-matrix calculation to obtain electronically inelastic collisional excitation cross sections; they then used a high-level electronic structure calculation to determine excited state energies and derivative couplings, and trajectory surface hopping to determine branching in the dissociation of the methane.…”

Quantum‐Mechanical Calculations of Cross Sections for Electron Collisions With Atoms and Molecules

“…The agreement between the RMPS/MRCI model of Brigg et al and the recommended (experimental) result is good. The SEP calculations also give reasonable agreement, while the CC‐24 and CC‐48 calculations do not predict a Ramsauer minimum. The latter models do not account for coupling to the continuum via pseudo‐states and, therefore, underestimate the polarization effects.…”