<i>Ab initio</i> Hartree–Fock and configuration‐interaction treatment of the interaction between two nickel atoms

Abstract

Abstract The interaction between two nickel atoms in the configurations (3 d ) 8 (4 s ) 2 and (3 d ) 9 (4 s ) 1 has been calculated using ab initio methods (Hartree–Fock and configuration interaction). The results of the calculations compare favorably with the optical spectrum. The discrepancy between the calculated and the experimental dissociation energy is discussed, and a new estimate of the dissociation energy is given. The configuration‐interaction calculations show that the interaction between the two nickel atoms is of a very complex nature. In spite of this the binding can be interpreted in a simple way. The bond is minly due to the 4 s σ g molecular orbital while the 3 d orbitals of the two nuclei are exchange coupled.