ANALYTIC BORN COMPLETION IN THE CALCULATION OF ELECTRON-MOLECULE DIFFERENTIAL CROSS-SECTIONS

In calculating the elastic differential cross section for electron sca ttering from linear nonpolar molecules, one must include elements of t he transition matrix corresponding to a large number of partial waves in order to obtain convergence at small angles. We present an analytic correction to the widely used expression for the differential cross s ection in terms of body-frame T-matrix elements calculated in the fixe d-nuclear-orientation approximation. This correction incorporates cont ributions from all high-order partial waves via the Born approximation . It efficiently produces accurate differential cross sections and sho ws rapid convergence even at small angles. We illustrate the importanc e and accuracy of this procedure for low-energy (less than 10 eV) coll isions of electrons with H-2 and N-2.