Pressure dependency of electron-phonon renormalization in diamond

- Many body calculation is used to evaluate electron and phonon self energies under external pressures.
- Changing the external pressure causes a transition from small to large polaronic behavior.
- Renormalization of valence carriers due to the interaction with phonons are large with pressures.

Employing ab initio many-body perturbation theory, the carrier-phonon and carrier-carrier vertex functions are evaluated in diamond crystal under different hydrostatic pressure up to 140 GPa and the phonon induced quasiparticle renormalization is measured at diverse linear and non-linear pressure regimes. Our results illustrate that the degree of carrier coupling to phonon satellite differs substantially from linear to non-linear regimes, due to changing the nature of the carrier dynamics. Particularly, reduction of the phonon induced renormalization with increasing pressure on the system is an indication of a transition from strong to a weak polaronic nature, which is in good accordance with experimental and theoretical studies. It demonstrates the significant role of the pressure in tuning the electron phonon coupling in a system. Furthermore, going to the higher pressure yields relevant discrepancy in electron energies from second-order phonon-induced to the first-order phonon perturbation. Our study recommends the hydrostatic pressure adjusts the significant contribution of electron-phonon self-energy in the electronic-related features of carbon-based materials as a new probe.