Surface Green function method for inhomogeneous multilayered systems

Inhomogeneous multilayered structures – e.g., interfaces between bulk substrates and one or more monolayered materials, van-der-Waals heterostructures, and Janus particles – exhibit electronic and magnetic properties that depend not only on the identity of the surface layer but on the neighboring environment. This remains true in structures containing 2D materials such as graphene and MoS₂. Calculating the surface electronic structure of such systems is complicated by both the need for periodic simulation cells in most first-principles approaches and the assumption of homogeneity in existing codes that compute surface Green functions and/or simulate ARPES experiments. Using DFT+Wannier90 tight-binding Hamiltonians as a starting point, we have generalized the method of López Sancho et al. to allow for inhomogeneous layered structures and present calculations of the surface electronic spectra of monolayer FeSe on SrTiO₃ as well as systems containing MoSe₂ / MoS₂ interfaces.