While most electronic structure studies on semiconductor surfaces have relied on the use of slab models and DFT, SCEs can also be modelled as semi-infinite surfaces using DFT-based Green function approaches. The Green function methods treat the semiconductor surface as part of a semiinfinite device consisting of bulk, surface, and vacuum regions. The bottomside of the surface is connected to the semiconductor bulk through electrostatic boundary conditions and a self-energy matrix while the top-side surface is connected to vacuum-like pseudoelectrode modelled through electrostatic boundary conditions. The configuration leads to solving a matrix equation of the entire device and yields a self-consistent solution for the electronic density and energy.