Total cross sections (TCSs) for electron scattering by polyatomic molecules ${\mathrm{C}}_2{\mathrm{F}}_4,$ ${\mathrm{C}}_2{\mathrm{F}}_6,$ ${\mathrm{C}}_3{\mathrm{F}}_6,$ ${\mathrm{C}}_3{\mathrm{F}}_8,$ ${\mathrm{C}}_6{\mathrm{F}}_6,$ and ${\mathrm{C}}_6{\mathrm{H}}_6$ are calculated in the incident electron energy range 30–3000 eV employing the 100% additivity rule and energy-dependent geometric additivity rule (EGAR) approaches. The EGAR, proposed by Jiang et al. [J. Phys. B 30, 5025 (1997); Phys. Lett. A 237, 53 (1997)], relates to molecular properties and the energy of incident electrons. Two approaches for the TCS of ${\mathrm{C}}_2{\mathrm{F}}_6,$ ${\mathrm{C}}_3{\mathrm{F}}_8,$ ${\mathrm{C}}_6{\mathrm{F}}_6,$ and ${\mathrm{C}}_6{\mathrm{H}}_6$ molecules are compared and the EGAR yields better accord with available experimental measurements in the whole energy region. The new results for ${\mathrm{C}}_2{\mathrm{F}}_4$ and ${\mathrm{C}}_3{\mathrm{F}}_6$ are also presented although no experimental data are available for comparison. The atoms are presented by spherical complex optical potential, which is composed of static, exchange, polarization, and absorption terms.

• Received 2 May 2000

DOI:https://doi.org/10.1103/PhysRevA.62.062712