HETERONUCLEAR TRANSITION-METAL DIATOMICS - THE BONDING AND ELECTRONIC-STRUCTURE OF SCNI, YNI, SCPD, AND YPD

High quality ab initio calculations show that ScNi, YNi, ScPd, and YPd all have 2-SIGMA+ ground states in agreement with electron spin resonance experiments. For ScNi and YNi, this is expected based on the lowest atomic asymptote. For ScPd and YPd, the lowest atomic asymptote would give the order of stability 2-DELTA > 2-PI almost-equal-to 2-SIGMA+, but the calculations show that mixing in of the excited asymptotes preferentially lowers the 2-SIGMA+ state. The calculations show that the quartet states are about 20-30 kcal/mol above the ground state, and therefore probably do not contribute significantly to the unexpected g perpendicular-to values found in experiment. Calculations of excited states for YPd reveal some strong transitions that should be amenable to spectroscopic studies.