Additivity rule for the calculation of electron scattering from polyatomic molecules

Abstract

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.