CONTINUUM WAVE-FUNCTIONS CALCULATIONS WITH LEAST-SQUARES SCHEMES IN A B-SPLINES BASIS

A diagonalization algorithm recently proposed for the continuum wavefunctions calculation is studied in the context of least-squares approaches. Other schemes are obtained and their convergence properties and accuracy are compared. Excellent convergence in the case of the Coulomb problem in a spline functions basis is achieved by all schemes, although significantly superior accuracy at the same level of treatment is afforded by the truly least-squares formulations. The computational advantages due to the symmetric and positive-definite nature of the matrix involved in the latter approaches are investigated in a single one-centre expansion for the H-2+ system, and may well offset the additional complexity involved.