R -matrix calculations of electron collisions with a lithium atom at low energies

Abstract

$R$-matrix calculations of the electron collisions with lithium atom at energies below the $3s$ excitation threshold are presented. The $^1S^e$, $^3S^e$ and $^1P^o$ phase shifts calculated in the near-threshold energy range are in excellent agreement with previous theoretical studies. The threshold behavior of the $^3P^o$ phase shift is accurately analyzed along with the resonance located at the scattering energy $\sim60$ meV. The phase shifts and cross sections calculated here show two resonances below the $3s$ threshold that have not been previously reported.