Real-time GW: Toward an ab initio description of the ultrafast carrier and exciton dynamics in two-dimensional materials

TL;DR

This paper demonstrates a time-linear scaling $GW$ method for ab initio simulations of ultrafast carrier and exciton dynamics in 2D materials, revealing non-Markovian effects and a screening cascade leading to Mott transition.

Contribution

It introduces a time-linear scaling formulation of the $GW$ method for real-time simulations of 2D materials, capturing non-Markovian and dynamical screening effects.

Findings

Carrier multiplication and relaxation in graphene show deviations from exponential behavior.

Discovery of a self-sustained screening cascade in semiconductors leading to Mott transition.

Emphasizes the importance of non-Markovian effects in out-of-equilibrium phenomena.

Abstract

We demonstrate the feasibility of the time-linear scaling formulation of the $GW$ method [Phys. Rev. Lett. {\bf 124}, 076601 (2020)] for {\it ab initio} simulations of optically driven two-dimensional materials. The time-dependent $GW$ equations are derived and solved numerically in the basis of Bloch states. We address carrier multiplication and relaxation in photo-excited graphene and find deviations from the typical exponential behavior predicted by the Markovian Boltzmann approach. For resonantly pumped semiconductor we discover a self-sustained screening cascade leading to the Mott transition of coherent excitons. Our results draw attention to the importance of non-Markovian and dynamical screening effects in out-of-equilibrium phenomena.