Electron scattering from silicon

Abstract

The $B$-spline $R$-matrix method is used to study electron collisions with neutral silicon over an energy range from threshold to 100 eV. The multiconfiguration Hartree-Fock method with nonorthogonal orbitals is employed for an accurate representation of the target wave functions. The present close-coupling expansion includes 34 bound states of neutral silicon derived from the [Ne]$3{s}^{2}\phantom{\rule{0.16em}{0ex}}3{p}^{2}$, $3s3{p}^{3}$, $3{s}^{2}\phantom{\rule{0.16em}{0ex}}3p4s$, $3{s}^{2}\phantom{\rule{0.16em}{0ex}}3p5s$, $3{s}^{2}\phantom{\rule{0.16em}{0ex}}3p4p$, $3{s}^{2}\phantom{\rule{0.16em}{0ex}}3p5p$, $3{s}^{2}\phantom{\rule{0.16em}{0ex}}3p3d$, and $3{s}^{2}\phantom{\rule{0.16em}{0ex}}3p4d$ configurations, plus seven pseudostates to fully account for the dipole polarizability of the ground state and the lowest three excited states of atomic silicon. Cross sections are presented for important transitions from the $3{s}^{2}\phantom{\rule{0.16em}{0ex}}3{p}^{2}{\phantom{\rule{0.16em}{0ex}}}^{3}\phantom{\rule{-0.16em}{0ex}}P$ ground state and the metastable $3{s}^{2}\phantom{\rule{0.16em}{0ex}}3{p}^{2}{\phantom{\rule{0.16em}{0ex}}}^{1}\phantom{\rule{-0.16em}{0ex}}D$ and $3{s}^{2}\phantom{\rule{0.16em}{0ex}}3{p}^{2}{\phantom{\rule{0.16em}{0ex}}}^{1}\phantom{\rule{-0.16em}{0ex}}S$ states. Both correlation and polarization effects are found to be important for accurate calculations of the cross sections. The sensitivity of the results was checked by comparing data obtained in different approximations. The current predictions represent an extensive set of electron scattering data for neutral silicon.