Direct ionization of low-charge Li-like ions using a small pseudo-state basis

We have calculated cross sections for the direct ionization of Be+, B2+ and C3+ by electron impact using a small pseudo-state basis within the R-matri x method (RMPS). On using one pseudo-state per l to represent the continuum , close agreement with converged RMPS results is obtained at energies great er than or similar to 3 times the ionization limit provided that the cross sections to the pseudocontinuum are projected back onto the physical contin uum. On using two pseudo-states per l, the close agreement is extended back down to energies below the ionization peak, again, provided that projectio n is used. The use of a small pseudo-state basis is necessary to describe i onization processes in more complex systems.