Accurate model Hamiltonian for Hg_3-δAsF₆ using nonatom-centred Wannier functions

A model Hamiltonian has been formulated for Hg_{3- delta}AsF ₆ embedded in the I4₁/amd space group based on eight Wannier functions constructed from gaussians. The authors centre the gaussian orbitals, and thus the Wannier functions, on special sites, which do not coincide with the mercury atoms but are related to the Wyckoff positions for the embedding I4₁/amd space group. Near the Fermi energy the model Hamiltonian, an 8*8 matrix, simulates accurately the bands resulting from an ASW calculation which used 160 basis functions.