Stopping dynamics of ions passing through correlated honeycomb clusters

TL;DR

This study develops a quantum-classical hybrid approach to analyze how ions lose energy when passing through correlated electron systems, revealing the impact of electron-electron interactions on stopping power in 2D materials.

Contribution

It introduces a combined nonequilibrium Green functions-Ehrenfest dynamics method for time-dependent energy loss studies in strongly correlated systems.

Findings

Electron-electron correlations significantly affect stopping power.

Results align with ab-initio simulations for graphene.

Energy exchange dynamics depend on correlation strength.

Abstract

A combined nonequilibrium Green functions-Ehrenfest dynamics approach is developed that allows for a time-dependent study of the energy loss of a charged particle penetrating a strongly correlated system at zero and finite temperature. Numerical results are presented for finite inhomogeneous two-dimensional Fermi-Hubbard models, where the many-electron dynamics in the target are treated fully quantum mechanically and the motion of the projectile is treated classically. The simulations are based on the solution of the two-time Dyson (Keldysh-Kadanoff-Baym) equations using the second-order Born, third-order and T-matrix approximations of the self-energy. As application, we consider protons and helium nuclei with a kinetic energy between 1 and 500 keV/u passing through planar fragments of the two-dimensional honeycomb lattice and, in particular, examine the influence of electron-electron correlations on the energy exchange between projectile and electron system. We investigate the time dependence of the projectile's kinetic energy (stopping power), the electron density, the double occupancy and the photoemission spectrum. Finally, we show that, for a suitable choice of the Hubbard model parameters, the results for the stopping power are in fair agreement with ab-initio simulations for particle irradiation of single-layer graphene.