Variational calculations of accuratee−-He cross sections below 19 eV

Variational calculations of $s$- and $p$-wave phase shifts for $e^{-}$-He scattering have been carried out for energies less than 19 eV. The variational wave function represents target-atom electronic correlation, electric dipole and quadrupole polarizability response, and short-range electron-atom correlation at a level of accuracy sufficient for 1% accuracy in the differential cross section. The partial-wave Born approximation is used for phase shifts $l>\mathrm{}1\mathrm{}$. Calculated phase shifts are corrected for estimated systematic errors, and these estimated phase shifts are interpolated as smooth functions of energy by cubic spline fits to auxiliary interpolating functions. Comparison with recent experimental and theoretical cross section data indicates compatibility with the present error estimate of no more than 1%. Data given here make it possible to compute the differential cross section from simple formulas over the energy range considered. The present value of the scattering length is $1.1835a_0$ with 0.5% error.