The R-matrix method has been used with great success in recent years to mod
el low energy scattering of electrons and positrons by molecules. The codes
, developed by a consortium of UK research groups as part of the Collaborat
ive Computational Project 2 (CCP2), have now reached a high level of robust
ness and stability Their overall design is described in this paper, (C) 199
8 Elsevier Science B.V.