Ab initio restricted Hartree—Fock and configuration interaction calculations for Li3

Calculations of the energies for various geometries of Li3, involving linear and perpendicular approaches of a Li atom to a Li2 molecule, are described. The basis set was of double zeta plus polarization contracted gaussian orbitals, and both a single configuration restricted Hartree—Fock function, and a five configuration function were used. The perpendicular approach was found to give the lowest energy, and the most stable form of Li3 is estimated to be about 10 kcal/mole lower in energy than Li + Li2.