LCAO EXPANSION IN A SPLINE BASIS FOR ACCURATE VARIATIONAL DETERMINATION OF CONTINUUM WAVE-FUNCTIONS - APPLICATIONS TO H2(+) AND HEH2+

The purely algebraic variational approach in a spline basis, which has recently given sub-nanohartree accuracy in the LCAO expansion of H-2+ and HeH2+ bound states, has been applied also to the continuum wavefunction calculations of these molecules. An efficient algorithm to treat linear dependence problems without loss of accuracy is presented. The accuracy in cross section calculations, with few angular momenta, is further improved beyond the maximum one-center limit (with lmax = 50 and lmax = 35) previously obtained. The LCAO scheme proposed may yield accurate continuum orbitals for general polyatomic molecules.