Later studies distinguished between bulk and surface electronic properties, considering that the catalytic properties should be mainly related to the surface electronic structure, in addition to geometric effects. Furthermore, the focus changed to a local picture, using the local density of states (LDOS) on the respective surface atoms. This is particularly important for bimetallic surfaces, where the electronic properties of the two different types of surface atoms should be different. But similar effects are expected also for structural defects, as the electronic properties of a step edge atom are different from those of terrace surface atoms.