Isomerism of Ni cluster anions and its role on photo-detachment spectroscopy

First principles calculations based on density functional theory and the generalized gradient approximation reveal that a Ni dimer anion can exist in two nearly degenerate forms characterized by different bond lengths and spin multiplicities. Similarly Ni3− exhibits two isomeric forms — a linear chain and an equilateral triangle but both having the same quartet spin multiplicity and protected by an energy barrier of about 0.8 eV. The existence of these isomers impacts strongly on the interpretation of the experimental photo-detachment spectra.