Electron impact excitation of n=3 and 4 states of Be

The R-matrix method is used to obtain collision strengths for e - -Be scattering for transitions between the n=2, 3 and 4 levels. Three calculations are described. Firstly, a 12-state calculation is carried out with exchange including all the n=2 and 3 levels for energies from threshold to 7 Ryd. Secondly, this 12-state calculation is repeated omitting exchange. Finally, a 20-state no-exchange calculation including all n=2, 3 and 4 levels for energies from threshold to 4 Ryd is carried out. The target states in all three calculations are obtained using optimized configuration interaction expansions.