U+3 bound and continuum states in e - He2+ scattering

Ab initio calculations are performed on the e - He2+ complex using the R-matrix technique. A two-state approximation is utilized in which the u+2 and the A g+2 electronic states of He2+, in the close-coupling expansion, are represented by truncated configuration-interaction (CI) wave functions obtained from multiconfiguration-self-consistent-fieldcomplete-active-space-SCF (MCSCF-CASSCF) calculations. A (4s,2p,2d) Slater basis is used to perform bound-state calculations at SCF, full CI, and MCSCF-CASSCF levels, to gauge the quality of wave functions at various bond separations. Elastic cross sections are presented for selected bond lengths in the range 1.54.0a0, for the u+3 total symmetry. He2*(1g1u2np and nf u+3) resonances are detected at each separation and fitted to Breit-Wigner formulas in order to determine their energies and autoionization widths. In addition, low-lying He2*(1g21uns, nd, and ng 3u+) bound states are also calculated at several geometries.