Coherent phonons in photoexcited semiconductors from first principles
Abstract
Coherent phonons are phase-locked lattice vibrations that provide a sensitive probe of nonequilibrium dynamics in materials. Existing first-principles equation-of-motion (EOM) approaches have successfully described coherent phonons in metals and semimetals, but their extension to semiconductors requires treating the long-lived electron--hole plasma created by above-gap excitation. Here we extend the first-principles EOM framework to photoexcited semiconductors by incorporating the residual plasma force that shifts the lattice equilibrium together with the plasma-induced renormalization of the electronic structure. For monolayer MoTe2, the calculated carrier-density-dependent Te displacement agrees with constrained density-functional perturbation theory only when the renormalized band structure is included. We then show that increasing the photoexcited carrier density enhances both the initial total force and the plasma-shifted equilibrium position of the A1g mode, producing larger coherent lattice oscillations. This density-controlled response appears in both the atomic displacement and the coherent-phonon-induced band renormalization, providing complementary signatures for ultrafast reflectivity and time- and angle-resolved photoemission spectroscopy.
Versions
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BibTeX
@misc{qiu2026coherent,
title = {{Coherent phonons in photoexcited semiconductors from first principles}},
author = {Yuhui Qiu and Rong-Tian Pang and Meng-Xue Guan and Jin-Jian Zhou},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.22901},
eprint = {2610.22901},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.22901},
}
RIS
TY - UNPB
TI - Coherent phonons in photoexcited semiconductors from first principles
AU - Yuhui Qiu
AU - Rong-Tian Pang
AU - Meng-Xue Guan
AU - Jin-Jian Zhou
PY - 2026
DA - 2026/10/16
PB - arXiv
DO - 10.48550/arxiv.2610.22901
UR - https://arxiv.org/abs/2610.22901
AB - Coherent phonons are phase-locked lattice vibrations that provide a sensitive probe of nonequilibrium dynamics in materials. Existing first-principles equation-of-motion (EOM) approaches have successfully described coherent phonons in metals and semimetals, but their extension to semiconductors requires treating the long-lived electron--hole plasma created by above-gap excitation. Here we extend the first-principles EOM framework to photoexcited semiconductors by incorporating the residual plasma force that shifts the lattice equilibrium together with the plasma-induced renormalization of the electronic structure. For monolayer MoTe_2, the calculated carrier-density-dependent Te displacement agrees with constrained density-functional perturbation theory only when the renormalized band structure is included. We then show that increasing the photoexcited carrier density enhances both the initial total force and the plasma-shifted equilibrium position of the A_1g mode, producing larger coherent lattice oscillations. This density-controlled response appears in both the atomic displacement and the coherent-phonon-induced band renormalization, providing complementary signatures for ultrafast reflectivity and time- and angle-resolved photoemission spectroscopy.
ER -