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 wavefu nction calculations of these molecules. An efficient algorithm to trea t linear dependence problems without loss of accuracy is presented. Th e 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.