Orbitalwise Coordination Number for Predicting Adsorption Properties of Metal Nanocatalysts

We present the orbitalwise coordination number CN alpha (alpha = s or d) as a reactivity descriptor for metal nanocatalysts. With the noble metal Au (5d(10)6s(1)) as a specific case, the CNs computed using the twocenter s-electron hopping integrals to neighboring atoms provides an accurate and robust description of the trends in CO and O adsorption energies on extended surfaces terminated with different facets and nanoparticles of varying size and shape, outperforming existing bond-counting methods. Importantly, the CNs has a solid physiochemical basis via a direct connection to the moment characteristics of the projected density of states onto the s orbital of a Au adsorption site. Furthermore, the CNs shows promise as a viable descriptor for predicting adsorption properties of Au alloy nanoparticles with size-dependent lattice strains and coinage metal ligands.