AB-INITIO CALCULATION OF THE ASYMMETRIC ELECTRON-TRANSFER CROSS-SECTION IN THE LOW-VELOCITY LI3++HE+ COLLISION

The (HeLi)(4+) one-electron molecule has been studied and the electron ic energies of the states n = 1-5 have been determined as a function o f the distance R between the two nuclei, in the Born-Oppenheimer appro ximation. The radial and rotational matrix elements for electron trans fer in the Li3+ + He+ collision have been computed and the system of 3 5 coupled equations describing the collision in the impact parameter a pproximation has been solved for an initial system composed of an inci dent Li3+ ion and a He+ target in the ground state. The signs of the d ifferent terms appearing in the radial matrix elements have been caref ully re-examined and a clear resonance induced by the avoided crossing of the 5d sigma and 4p sigma states has been proven. The Li3+ + He+ - -> Li2+ + He2+ total electron transfer cross section is found to lie b etween those of the adjacent symmetric systems He2+ + He+ and Li3+ + L i2+ and, in this respect, may be called 'quasisymmetric transfer'.