Models Overview
EmpiricalTightBinding.jl provides a hierarchy of tight-binding models with increasing complexity.
Model Comparison
| Model | Orbitals per atom | Bands | Spin-Orbit | Reference |
|---|---|---|---|---|
| SP3 | s, p | 8 | No | — |
| SP3Sstar | s, p, s* | 10 | No | Vogl et al. (1983) |
| SP3Sstar_SO | s, p, s* × spin | 20 | Yes | Klimeck et al. (2000) |
| SP3D5Sstar | s, p, d, s* | 20 | No | Jancu et al. (1998) |
Choosing a Model
- SP3: Simplest model. Gives qualitatively correct valence bands but poor conduction bands (no indirect gap in Si/Ge).
- SP3Sstar: Adds an excited s* orbital to fix the conduction band issue. The standard choice for most applications.
- SP3Sstar_SO: Adds spin-orbit coupling. Required for materials with significant spin-orbit (SO) splitting (e.g., InSb, GaSb).
- SP3D5Sstar: Adds d orbitals for improved accuracy across the full Brillouin zone. Best for quantitative work.