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Construction of optimized tight-binding models using ab initio Hamiltonian: application to monolayer 2H-transition metal dichalcogenides
KIAS Author
Kim, Sejoong
We present optimized tight-binding (TB) models with atomic orbitals to improve ab initio TB models constructed by truncating full density functional theory (DFT) Hamiltonian based on localized orbitals. Retaining qualitative features of the original Hamiltonian, the optimization reduces quantitative deviations in overall band structures between the ab initio TB model and the full DFT Hamiltonian. The optimization procedure and related details are demonstrated by using semiconducting and metallic Janus transition metal dichalcogenides monolayers in the 2 H configuration. Varying the truncation range from partial second neighbors to third ones, we show differences in electronic structures between the truncated TB model and the original full Hamiltonian, and how much the optimization can remedy the quantitative loss induced by truncation. We further elaborate the optimization process so that local electronic properties such as valence and conduction band edges and Fermi surfaces are precisely reproduced by the optimized TB model. We also extend our discussions to TB models including spin-orbit interactions, so we provide the optimized TB model replicating spin-related properties of the original Hamiltonian such as spin textures. The optimization process described here can be readily applied to construct the fine-tuned TB model based on various DFT calculations.