  In this paper we derive a formalism allowing us to separate inter-layer
contributions to the polarizability of a periodic array of 2D materials from
intra-layer ones. To this aim, effective profile functions are introduced. They
constitute a tight-binding-like layer-localized basis involving two lengths,
the effective thickness $d$ characteristic of the 2D material and the
inter-layer separation $L$. The method permits, within the same formalism,
either to compute the single-layer dielectric function from an ab-initio
periodic calculation (top-down strategy) or to stack several 2D materials to
generate a finite-thickness van der Waals heterostructure (bottom-up strategy).
