Theoretical Solid-State Physics

The Jena Electronic Theory and Spectroscopy (JETS) group explores the fundamental interactions governing the behavior of a diverse range of materials and nanostructures using ab initio quantum-mechanical methods. Our research focuses on the electronic structure and light-matter coupling of a variety of (complex) materials, ranging from organic to inorganic crystals, and from low-dimensional sheets to their heterostructures, including hybrid interfaces.

A strong emphasis is placed on investigating the response of these systems to external fields across the whole electromagnetic spectrum, ranging from the infrared region, triggering vibrations, to hard X-rays, probing the atomic fingerprints of materials. We examine both static and ultrafast dynamical regimes of excitations to uncover fundamental processes driven by weak and strong fields using a versatile portfolio of computational methods, ranging from (time-dependent) density-functional theory and many-body perturbation theory. Recent developments in high-throughput screening routines boost our abilities to efficiently explore elaborate configurational spaces.

Research areas

Prof. Cocchi’s research covers a wide range of topics across solid-state theory and computational materials science. Her group’s mission is to address grand societal challenges by guiding the design of sustainable materials for next-generation optoelectronic and photonic applications. Key topics include:

• Computational screening and design of materials
• Theoretical spectroscopy
• Laser-driven electronic and vibrational dynamics
• Nonlinear optical properties of materials

Teaching fields

Prof. Cocchi teaches basic and advanced topics in theoretical physics for both undergraduate and graduate students. She aims to connect fundamental physics and advanced computational methods to stimulate students’ curiosity and scientific creativity, with an eye for historical and personal aspects of science. Current teaching topics covered by her group include:

• Theoretical solid-state physics
• Undergraduate courses in theoretical physics
• Advanced quantum-mechanical methods for electronic theory and spectroscopy
• Python for scientific practice

Research methods

• (time-dependent) density functional theory
• Ehrenfest dynamics
• Many-body perturbation theory
• Solvation methods for layered substrates
• High-throughput screening algorithms with machine-learning integrations

 Prof. Cocchi’s research activities focus on the ab initio theoretical description and simulation of electronic properties, light-matter interactions, and excited-state dynamics in complex materials and nanostructures.

Recent Research Results

Prof. Cocchi’s group develops and applies quantum-mechanical methods for electronic-structure theory, spectroscopy, and dynamics. Their portfolio includes:

Low-Dimensional Materials and Heterostructures:

The emergence of two-dimensional (2D) systems and their van der Waals heterostructures offers a new playground for engineering quantum and nonlinear optical properties. We aim to understand how structural and morphological degrees of freedom modify the electronic structure of these systems and their (dynamical) response to light. Our work explores a wide range of systems, including transition-metal dichalcogenides (TMDs) and their interfaces with conjugated molecules. Recently, we have demonstrated the emergence of hybrid excitations in hBN/WSe2 heterostructures [1] and predicted the formation of quantum dots in TMDs induced by atomic-scale deformations [2].

Nonlinear Optics and Ultrafast Dynamics:

We investigate the dynamic interactions between organic, inorganic, and hybrid materials and intense electromagnetic fields using real-time time-dependent density-functional theory, in conjunction with Ehrenfest dynamics to describe nuclear motion. A primary focus is understanding how material composition and external field characteristics influence the nonlinear response of materials and molecules. We have recently pioneered the description of two-dimensional electronic spectroscopy from first principles [3], and showed that oligothiophene molecules, an established class of compounds for organic electronics, can host optical limiting in the near-infrared region [4]. Our simulations have also shed light on phonon-driven Rabi oscillations in halide perovskites [5] and laser-controlled charge transfer in 2D organic/inorganic nanojunctions [6]. These activities are integrated into large-scale collaborations, such as the SFB 1375 “Nonlinear Optics at the Atomic Scale (NOA).”

Modeling Sustainable Materials for Novel Applications

The discovery of sustainable materials is critical for addressing global societal challenges. We adopt state-of-the-art methods, ranging from high-throughput screening to many-body perturbation theory, to characterize materials for a wide range of relevant applications, including nonlinear optics, photovoltaics, and catalysis. To manage the vast configurational space of these materials and their functionalization, we developed the aim2datExternal link toolkit, an automated library for ab initio data analysis. Our research covers a broad spectrum of materials, from halide perovskites and metal-organic frameworks to multi-alkali antimonides for ultra-bright electron sources. Recently, we have successfully unraveled the complex electronic structure of nickel cobalt manganese oxides [7] and established new protocols for the automated analysis of surface facets in photocathode materials [8].