Research

My research is concerned with the question of how atomic and molecular few-body systems respond to perturbations exerted on them by impinging particles and external fields. Such collision or laser field induced quantum dynamics have implications for a variety of topics and applications ranging from plasma diagnostics to radiation biology. What is more, they constitute a problem of fundamental importance: How do the building blocks of matter interact and evolve in space and time? The better this question is answered the more is learned about a further issue that receives considerable attention: Can few-body quantum dynamics be manipulated purposefully and controlled actively? I have participated in a number of projects and activities to shed light on these issues by theoretical analysis and computations. The theoretical approaches used include density functional theory to deal with the many-electron problem, and both nonperturbative and perturbative quantum methods to describe the dynamics of the systems.

In the last few years we have been working on methods to describe ionization and fragmentation of multi-center molecules. Applications are concerned with, e.g., ion-induced fragmentation of water, which is a relevant process in the radiation damage of biological tissue.

Selected papers on ion-molecule collisions

1. A. Jorge, M. Horbatsch, and T. Kirchner, Multicharged-ion-water-molecule collisions in a classical-trajectory time-dependent mean-field theory, Phys. Rev. A 102, 012808 (2020)
2. H. J. Lüdde, T. Kalkbrenner, M. Horbatsch, and T. Kirchner, Nonperturbative scaling behavior for net ionization of biologically relevant molecules by multiply charged heavy-ion impact, Phys. Rev. A 101, 062709 (2020)
3. H. J. Lüdde, M. Horbatsch, and T. Kirchner, Proton-impact-induced electron emission from biologically relevant molecules studied with a screened independent atom model, J. Phys. B 52, 195203 (2019)
4. H. J. Lüdde, M. Horbatsch, and T. Kirchner, A screened independent atom model for the description of ion collisions from atomic and molecular clusters, Eur. Phys. J. B 91, 99 (2018)
5. H. J. Lüdde, A. Achenbach, T. Kalkbrenner, H.-C. Jankowiak, and T. Kirchner, An independent-atom-model description of ion-molecule collisions including geometric screening corrections, Eur. Phys. J. D 70, 82 (2016)
6. H. Luna, W. Wolff, E. C. Montenegro, A. C. Tavares, H. J. Lüdde, G. Schenk, M. Horbatsch, and T. Kirchner, Ionization and electron-capture cross sections for single- and multiple-electron removal from H₂O by Li³⁺ impact, Phys. Rev. A 93 052705 (2016)
7. T. Kirchner, M. Murakami, M. Horbatsch, and H. J. Lüdde, Ion collisions with water molecules: a time-dependent density functional theory approach, in: Advances in Quantum Chemistry, Vol. 65: Theory of Heavy Ion Collision Physics in Hadron Therapy, ed. by Dz. Belkic, (Elsevier, Amsterdam 2013)