We present a practical scheme for performing ab initio supercell calculations of charged
slabs at constant electron chemical potential μ, rather than at constant number of electrons N
e. To this end, we define the chemical potential relative to a plane (or “reference electrode”)
at a finite distance from the slab (the distance should reflect the particular geometry of the
situation being modeled). To avoid a net charge in the supercell, and thus make possible a
standard supercell calculation, we restore the electroneutrality of the periodically repeated …