THEORETICAL-STUDY OF SINGLE AND DOUBLE-CHARGE-TRANSFER IN HE2+-HE COLLISIONS AT KILO-ELECTRON-VOLT ENERGIES IN A DIABATIC MOLECULAR REPRESENTATION

A 15-state diabatic molecular expansion, covering channels up to 2s and 2p excitations, has been used to study single and double charge transfer in He2+ -He(1s(2)) collisions at kilo-electron-volt energies. The aim of the work has been to explore the usefulness of this type of diabatic molecular basis for eventual use in benchmark calculations, electron translation factors not being included in this low-energy calculation. Our results for single and double electron capture agree very well with experiment up to relative velocities of similar to 0.5-0.6 a.u. For single capture into the ground state the series can be truncated early with very little effect, but for double capture the truncation cannot be done. A probable connection with correlated two-electron motion is discussed.