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Main Authors: Bielke, Lina, Schöpa, Samuel, Wiechmann, Falk-Erik, Fennel, Franziska, Bauer, Dieter
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2512.02623
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author Bielke, Lina
Schöpa, Samuel
Wiechmann, Falk-Erik
Fennel, Franziska
Bauer, Dieter
author_facet Bielke, Lina
Schöpa, Samuel
Wiechmann, Falk-Erik
Fennel, Franziska
Bauer, Dieter
contents The generation of high harmonics is a strongly nonlinear effect that allows to probe properties of the target and to study electron dynamics in matter. It has been investigated in many different kinds of targets, including molecular gases, liquids and solids. Recently, high-harmonic generation was studied in organic molecular crystals by Wiechmann et al. [Nat. Commun. 16, 9890 (2025)]. It was found that the laser-polarization-dependent harmonic yield is sensitive to the weak couplings between nearest- and next-nearest-neighbor molecules. In this paper, the impact of the laser polarization angle and the intermolecular interaction on the harmonic yield is examined in detail using a simple but insightful two-dimensional tight-binding system that models a molecular dimer, i.e. two weakly coupled molecules. We find that the intensities of lower harmonic orders tend to maximize for a laser polarization direction aligning with the molecular axes, whereas higher harmonic orders rather show the strongest yield for a polarization direction along the intermolecular axis. We further demonstrate that the harmonic order at which the maximum flips from the molecular to the intermolecular direction strongly depends on the intermolecular coupling strength. To gain a deeper insight into the origins of the findings, we include a detailed adiabatic analysis, showing that the flipping of the maximum yield towards the intermolecular direction is already contained qualitatively in the adiabatically following states.
format Preprint
id arxiv_https___arxiv_org_abs_2512_02623
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle High-harmonic generation from two weakly coupled molecules: a simple tight-binding model
Bielke, Lina
Schöpa, Samuel
Wiechmann, Falk-Erik
Fennel, Franziska
Bauer, Dieter
Quantum Physics
Atomic Physics
Optics
The generation of high harmonics is a strongly nonlinear effect that allows to probe properties of the target and to study electron dynamics in matter. It has been investigated in many different kinds of targets, including molecular gases, liquids and solids. Recently, high-harmonic generation was studied in organic molecular crystals by Wiechmann et al. [Nat. Commun. 16, 9890 (2025)]. It was found that the laser-polarization-dependent harmonic yield is sensitive to the weak couplings between nearest- and next-nearest-neighbor molecules. In this paper, the impact of the laser polarization angle and the intermolecular interaction on the harmonic yield is examined in detail using a simple but insightful two-dimensional tight-binding system that models a molecular dimer, i.e. two weakly coupled molecules. We find that the intensities of lower harmonic orders tend to maximize for a laser polarization direction aligning with the molecular axes, whereas higher harmonic orders rather show the strongest yield for a polarization direction along the intermolecular axis. We further demonstrate that the harmonic order at which the maximum flips from the molecular to the intermolecular direction strongly depends on the intermolecular coupling strength. To gain a deeper insight into the origins of the findings, we include a detailed adiabatic analysis, showing that the flipping of the maximum yield towards the intermolecular direction is already contained qualitatively in the adiabatically following states.
title High-harmonic generation from two weakly coupled molecules: a simple tight-binding model
topic Quantum Physics
Atomic Physics
Optics
url https://arxiv.org/abs/2512.02623