First-Principles Wannier Representation of Proximity Effects
arXiv:2607.25690
The paper introduces a first‑principles method to construct a dynamical proximity operator from density functional theory, allowing exact downfolding of heterostructure Hamiltonians onto low‑energy Wannier subspaces and capturing energy‑dependent hybridization effects, demonstrated on graphene on hBN/Co, PtSe₂, and WSe₂.
Abstract
Proximity effects in layered heterostructures are usually represented by static parameters fitted to first-principles bands, which discards the energy dependence of the virtual hybridization, the momentum transfer, and the spatial structure. We overcome this limitation by deriving a dynamical proximity operator directly from density functional theory, downfolding the Kohn-Sham Hamiltonian of the heterostructure onto a fixed low-energy target Wannier subspace and reproducing its spectrum exactly within that subspace. The construction separates direct matrix elements from virtual hybridization through all remaining states. In graphene on hBN/Co(0001), virtual hybridization generates more than of the proximity exchange and gives it a resonant frequency dependence set by the Co states. In graphene/PtSe it resolves a sublattice-selective intervalley coupling with a charge modulation, and in graphene/WSe a bond-resolved Rashba coupling of ~meV, against below ~eV for the direct projection alone. Our results expose the limitations of static projections and establish a fitting-free microscopic foundation for low-energy modeling, spin-relaxation theory, and transport calculations.