Low-energy electron scattering by CF4, CCl4, SiCl4, SiBr4, and SiI4

in this paper, we show elastic and rotationally inelastic cross-section calculations of low-energy electron scattering by CF4, CCl4, SiCl4, SiBr4, and SiI4. The fixed-nuclei static-exchange scattering amplitudes were obtained with the Schwinger multichannel method with soft norm-conserving pseudopotentials. We show elastic integral and differential cross sections and discuss the role of the basis set on the nature of some structures seen in a previous publication [A. P. P; Natalense et al., Phys. Rev. A 52, R1 (1995)]. We have attributed these structures to linear dependency in the basis set caused by the symmetric combination (x(2)+y(2)+z(2))exp(-ar(2)). The rotational cross sections were calculated with the help of the adiabatic-nuclei-rotation approximation. Our results are in good agreement with available experimental data. The sums of 0 -->0,3,4,6 rotational cross sections in general show good agreement with the elastic (rotationally unresolved) ones. The rotationally summed integral cross section agrees within 0.3% with the elastic integral cross section for CF4 at 7.5 eV, and within 26% for SiI4 at 30 eV. It was found that rotationally inelastic cross sections are considerably large for such molecules, because the heavy peripheral atoms play a significant role as scattering centers. [S1050-2947(99)00611-3].