Magnetic coupling interaction for mixed transition metal dimer: Ab initio MRCI(SD) + Q investigation on CrCu

Ab initio calculations on the potential energy curves and electronic structures of the ground and low-lying electronic states for the mixed transition metal dimer CrCu have been carried out by using the internally contracted multireference singles and doubles configuration interaction method MRCI(SD) + Q. The spectroscopic constants of the selected electronic states were obtained. The results are presented supporting the 6Σ+ ground state, by contrast to the assigned ground state 4Σ in ESR of CrCu. The electronic structures of the ground state and the low-lying states are multireference in character, and the ground state 6Σ+ is mainly dominated by strong intra-atomic d–d exchange interactions on the atom Cr.