EXCHANGE EFFECTS IN THE TRANSITION AMPLITUDE FOR INELASTIC ELECTRON-CLUSTER COLLISIONS

The effect of the electronic exchange in the calculation of the scatte ring amplitude for inelastic electron-cluster collisions is evaluated. The target cluster initially in the ground state is excited, by means of the Coulomb forces, into a particle-hole state. An antisymmetrized transition amplitude is evaluated in the scope of the distorted-wave Born approximation. A comparison is made with a calculation in which t he exchange is taken into account by adding to the direct interaction a Coulomb exchange term in the Slater approximation. The treatments ar e applied to the closed-shell Nas cluster for incident energies up to 5 eV.