Abstract
The influence of relativity on the spectroscopic parameters of Cu2 has been investigated by evaluating the mass‐velocity and one electron Darwin terms of the Breit–Pauli Hamiltonian in the first order of perturbation theory. The relativistic corrections are of the order of 10% of the SCF and GVB results and result in a deeper (∼1.5 kcal), stiffer (∼15 cm1) well, with the bond length contracted by about 0.1a0. (AIP)