A new form for the close-coupling equations

Abstract
It is shown that the non-uniqueness of the scattering solutions of the close-coupling equations can be resolved in a natural way without recourse to the usual orthogonality conditions. The new equations have a different structure for the exchange terms but their computation involves no extra effort. Two examples based on the 1s-2s-2p close-coupling model for electron scattering by atomic hydrogen are given to illustrate the new form.