Ab initiostudy of vibrational excitation of HF by low-energy electrons

Fixed-nuclei, static-exchange calculations have been performed to study the vibrational-rotational excitation of HF by electrons from threshold to 5 eV. Our calculated, $R$-dependent $K$-matrix elements in ${}_{}{}^2{}_{}{}^{}\Sigma _{}^{+}{}_{}{}^{}$, ${}_{}{}^2{}_{}{}^{}\Pi$, and ${}_{}{}^2{}_{}{}^{}\Delta$ symmetry are combined with exact point-dipole and laboratory-frame first-Born-approximation results for higher symmetries to obtain converged, integrated cross sections. The calculations show strong threshold peaks which are related to the dependence of the ${}_{}{}^2{}_{}{}^{}\Sigma _{}^{+}{}_{}{}^{}$ $K$-matrix elements on internuclear distance at small scattering energies.