Table 1. Effects of External Pressure P on the Electronic Band Gap and the Excitonic Responsesa.
| P (GPa) | Eg (PBE/HSE06) (eV) | ΔEΓ (eV) | ExΓ–Γ (eV) | Exb (meV) | ExHb,1 (meV) |
|---|---|---|---|---|---|
| 0 | 1.36/1.73 | 4.130 | 4.000 | 133.0 | 23.66 |
| 15 | 1.12/1.40 | 3.899 | 3.830 | 70.0 | 18.35 |
| 30 | 0.81/1.16 | 3.661 | 3.608 | 53.0 | 18.75 |
| 44 | 0.40/0.88 | 3.496 | 3.448 | 48.0 | 17.92 |
| 59 | 0.07/0.59 | 3.388 | 3.335 | 54.0 | 19.00 |
| 74 | metal/0.40 | 3.327 | 3.272 | 55.0 | 18.49 |
| 88 | metal/0.15 | 3.306 | 3.244 | 62.0 | 17.93 |
| 103 | metal/0.02 | 3.316 | 3.243 | 73.0 | 17.32 |
| 118 | metal/metal | 3.354 | 3.261 | 93.0 | 20.19 |
a
Here, Eg denotes the electronic band gap obtained using PBE and HSE06 frameworks, ΔEΓ denotes the HSE06-based Γ–Γ points energetic difference, ExΓ–Γ denotes the exciton state energy at the Γ point (MLWF-TB+BSE), Exb denotes the corresponding exciton binding energy (MLWF-TB+BSE) obtained by the difference of ΔEΓ – ExΓ–Γ, and ExHb,1 is the ground state exciton binding energy calculated from the hydrogenic model.