Is it possible to calculate electronegativity of surface atoms?

As the title asks, is it possible to calculate the electronegativity (EN) of specific atoms on extended surfaces (slabs), more specifically using computational methods? There are a few issues here I am running into:


To find the Mulliken EN $\chi$, we can use the relation 


$$\chi = \frac{E\_\mathrm{i} + E\_\mathrm{ea}}{2}$$


where $E\_\mathrm{i} = E(\ce{M+}) - E(\ce{M})$ and $E\_\mathrm{ea} = E(\ce{M})-E(\ce{M-})$. However, these energies are for the entire system, usually a molecule, and not the individual atoms. I hope I am not misunderstanding the concept here. 


Alternatively certain definitions use $\chi = -\mu$, or the work function. Again, this is usually calculated on a surface basis, not per atom of site. 


Is there no accurate determination method which is specific to the atom? Or is it conceptually impossible?


