SIMPLEST DOUBLY-CHARGED NEGATIVE-ION - NONEXISTENCE OF H-2- RESONANCES

Two independent types of ab initio calculations for three electrons in the field of a proton have been carried out. Neither calculation shows any evidence for the existence of a resonant state of H-2- contributing to e+H- inelastic scattering, at energies above the three-electron escape threshold. One of the methods used is based on an eigenchannel R-matrix calculation carried out within a reaction volume of finite radius r0, followed by an averaging procedure over r0. A second method is based on a configuration-interaction study of the dependence of the 2s(2)2p(2) P0 resonance on the nuclear charge Z. These calculations suggest that previous experimental and theoretical studies of this system were in erroneous agreement that two P-2(0) resonances exist in H-2- above the three-electron escape threshold. We also show that the earlier apparent agreement between experimental and theoretical resonance properties would violate unitarity of the collision matrix.