====== Program ======
Our workshop in Heidelberg will run from Monday morning, 5 October 2026, to Friday lunchtime, 9 October 2026. The programme alternates between lecture-based theory sessions and hands-on tutorials. We expect participants to arrive on Sunday evening (or early on Monday morning) and to leave on Friday.
The tutorials we use can be found at our [[https://git.quanty.org/Quanty/tutorials|git server]] and cloned with "git clone https://git.quanty.org/Quanty/tutorials.git". If you already have cloned the tutorials and want to update the latest changes, please use "git pull". If you have no git installed you can [[https://git.quanty.org/Quanty/tutorials/-/archive/main/tutorials-main.zip?ref_type=heads|download the full set of tutorials]] as https://git.quanty.org/Quanty/tutorials/-/archive/main/tutorials-main.zip?ref_type=heads (1.3 Gb)
^ ^ Sunday 4-10-2026 ^ Monday 5-10-2026 ^ Tuesday 6-10-2026 ^ Wednesday 7-10-2026 ^ Thursday 8-10-2026 ^ Friday 9-10-2026 ^
| 9:00 - 10:30 | ::: |**Lecture Robert Green ** \\ One Hamiltonian, Many Approximations: An Introduction to Embedded Methods ((**Monday 9:00 - Robert Green** Solving the full Hamiltonian of a correlated solid is hopeless, but core-level spectroscopy is local, and that suggests a way forward: treat a small region exactly and replace the rest of the crystal by an effective environment. Using NiO as a running example, this lecture builds up the hierarchy from atomic multiplets through crystal-field, ligand-field and Anderson impurity models to DMFT, showing that they are all the same Hamiltonian with an increasingly faithful description of that environment.)) \\ **Powerpoints** \\ {{ :workshop:heidelberg:october_2026:green_quanty2026_monday_morning.pptx |One Hamiltonian,
Many Approximations}} |**Lecture Marie-Anne Arrio ** \\ Atomic Multiplet theory and Crystal field Multi-electron ions ((**Tuesday 9:00 - Marie-Anne Arrio** The open 3d or 4f shell of a transition-metal or rare-earth ion determines many of its chemical and physical properties. This lecture first builds the free-ion Hamiltonian: the Coulomb interaction expressed through Slater integrals, the resulting spectroscopic terms, and spin-orbit coupling, including the two open shells created by a core hole. It then places the ion in a crystal, using point-group symmetry to derive crystal-field splittings and Tanabe-Sugano diagrams, with spin crossover as an example. Finally, a magnetic field is added to show how the crystal field shapes magnetic moments, paramagnetic susceptibility and magnetic anisotropy.)) \\ **Powerpoints** \\ {{ :workshop:heidelberg:october_2026:arrio-atom-crystal-field-heidelberg-2026.pdf | Atomic physics and crystal fields}}| **Lecture Robert Green ** \\ Beyond One Site: Multi-site Effects in Core-Level Spectroscopy ((**Wednesday 9:00 - Robert Green** The single-site models of the first two days assume that a transition-metal ion's neighbours act only as a bath. This lecture shows what happens when that assumption breaks down. Double-cluster models capture intersite charge fluctuations and bond disproportionation in negative charge-transfer perovskite nickelates, and Anderson impurity models with a band-like bath explain the dispersing charge-transfer features in the RIXS of NiO.
)) \\ **Powerpoints** \\ {{ :workshop:heidelberg:september_2024:groot_xas.pptx
| T.B.A. }} |**Lecture Sina Shokri and Kevin Ackermann ** \\ DFT based calculations \\ ((**Thursday 9:00 Kevin Ackerman and Sina Shokri** An introduction to Kohn-Sham density functional theory and its use for spectroscopic applications. Practical consideration when DFT might be sufficient and when not. Followed by a hands-on introduction to FPLO for the example of fcc Al, laying the groundwork for the Wannier downfolding and DFT+DMFT sessions thereafter.))\\ **Powerpoints** \\ {{ :workshop:heidelberg:september_2024:groot_rixs.pptx
| T.B.A. }} |**Lecture Marius Retegan** \\ Calculations using Crispy, a graphical interface \\ **Codes** \\ [[https://www.esrf.fr/computing/scientific/crispy/index.html|Crispy, a graphical interface]] \\ **Powerpoints** \\ {{ :workshop:heidelberg:september_2024:retegan_crispy.pptx | Crispy, a graphical interface }} |
|10:30 - 11:00 | ::: | **Coffee** | **Coffee** | **Coffee** | **Coffee** | **Coffee** |
|11:00 - 12:30 | ::: |**Hands-on tutorials** \\ A deep dive: Material realistic calculations of correlated electron systems. Band-structure, photo-electron spectroscopy, and x-ray absorption. \\ **Tutorials** \\ {{ :workshop:heidelberg:october_2026:06_dynamical_mean_field_theory.zip |DMFT of NiO, ground-state XAS and cPES}} \\ {{ :workshop:heidelberg:october_2026:01_introduction_to_quanty.zip | Introduction to Quanty}} |**Hands-on tutorials** \\ Atomic multiplet theory. Crystal field theory, Ligand field theory. Ground-state calculations and temperature (Boltzmann statistics). Magnetic susceptibility. \\ **Tutorials** \\ {{ :workshop:heidelberg:october_2026:03_atomic_physics.zip |Atomic physics}} \\ {{ :workshop:heidelberg:october_2026:04_crystal_field_theory.zip | Crystal-field theory}} \\ {{ :workshop:heidelberg:october_2026:05_ligand_field_theory.zip | Ligand-field theory}}|**Hands-on tutorials** \\ Crystal field theory, Ligand field theory and Anderson impurity models for many different spectroscopy techniques (XAS, //L23// and //K//-edge, Fluorescence yield //L23M45// and //L23M1//, RIXS core valence and core core excitations, nIXS valence and core excitations, PES, corePES, IPES and XES) \\ **Tutorials** \\ {{ :workshop:heidelberg:october_2026:08_materials.zip | Many spectroscopy examples on NiO}} |**Hands-on tutorials** \\ DFT calculations using FPLO. Convergence, band-structure and partial density of states compared to PES, ARPES and K-edge XAS \\ **Tutorials** \\ {{ :workshop:heidelberg:september_2024:07_thursday_morning_rixs.zip | T.B.A. }} \\ |**Hands-on tutorials** \\ Calculations using Crispy, a graphical user interface \\ **Tutorials** \\ {{ :workshop:heidelberg:september_2024:crispy_python_notebooks.zip | Python notebooks running Crispy }}\\ |
|12:30 - 13:30 | ::: | **Lunch** | **Lunch** | **Lunch** | **Lunch** | **Lunch** |
|13:30 - 15:00 | ::: |** Lecture Frank M.F. de Groot** \\ X-ray Spectroscopy: Overview and experimental aspects ((**Monday 13:30 - Frank de Groot** In order to perform simulations of x-ray spectroscopies, it is important to have a good understanding in the experimental procedures that are used to obtain x-ray spectra. In this lecture first an overview is given of the core level spectroscopies that can be performed with x-rays and with electrons. We discuss the basic interpretation of x-ray absorption spectra. The last part of the lecture discuss the different methods to measure an XAS spectrum, where the three main methods are transmission, electron yield and fluorescence yield. )) \\ **Powerpoints** \\ {{ :workshop:heidelberg:october_2026:heidelberg26_xray_spectroscopy.pptx | X-ray Spectroscopy: Overview and experimental aspects }} |**Lecture Frank M.F. de Groot** \\ Interpretation of X-ray absorption and X-ray photoemission ((**Tuesday - 13:30 Frank de Groot** Based on the atomic multiplet theory and crystal field theory, the 2p x-ray absorption spectral shape is explained, where we analyze the symmetry aspects of some XAS and X-MCD spectra. The effects of screening are discussed in the charge transfer multiplet theory of XAS and XPS spectral shapes.)) \\ **Powerpoints** \\ {{ :workshop:heidelberg:october_2026:heidelberg26_xasxps_multiplets.pptx | Interpretation of X-ray absorption and X-ray photoemission }} |**Lecture Michelangelo Tagliavini ** \\ Polarisation, geometry dependence, sum rules and tensor formulation in XAS and RIXS ((**Wednesday 13:00 - Michelangelo Tagliavini** Measuring how an x-ray spectrum depends on the polarisation of the light and the orientation of the sample reveals properties that an averaged measurement hides. There are infinitely many possible measurement geometries, but not all of them give different information. Starting from the dipole and quadrupole transition operators, this lecture explains x-ray linear and magnetic circular dichroism, and the sum rules that relate XMCD to the spin and orbital magnetic moments. It then shows that all of these effects are contained in a single conductivity tensor, whose form follows from the local point-group symmetry. There are straightforward relations between the tensor elements, the point-group symmetry and the material properties. In the second part, the tensor formulation is extended to RIXS. The 3 by 3 conductivity tensor of absorption (a three-dimensional rank-2 tensor) becomes a three-dimensional rank-4 tensor for RIXS. We can write it as a 9 by 9 matrix, using spherical tensors as its basis. As for absorption, this allows us to relate the tensor elements to the point-group symmetry and to material-specific properties.)) \\ **Powerpoints** \\ {{ :workshop:heidelberg:september_2024:haverkort_ab_initio_embedded_cluster_methods.pptx
| T.B.A. }} |**Lecture Maurits W. Haverkort ** \\ Ab initio many-body techniques \\ **Powerpoints** \\ {{ :workshop:heidelberg:september_2024:haverkort_ab_initio_embedded_cluster_methods.pptx
| DFT+MLFT and DFT+DMFT }} | **Departure** |
|15:00 - 15:30 | ::: | **Coffee** | **Coffee** | **Coffee** | **Coffee** | ::: |
|15:30 - 17:00 | ::: |**Hands-on tutorials** \\ Introduction to Quanty. (Orbitals, Slater-determinants, many-particle eigenstates, configuration interaction, restricted active space, Green’s functions, Self energy) \\ **Background literature** \\ [[https://www.lua.org|Lua Reference Manual]] \\ **Tutorials** \\ {{ :workshop:heidelberg:october_2026:01_introduction_to_quanty.zip | Introduction to Quanty}} \\ {{ :workshop:heidelberg:october_2026:99_plots.zip | Plotting in Quanty}}|**Hands-on tutorials** \\ Crystal field theory, Ligand field theory and Anderson impurity models for many different spectroscopy techniques (XAS, L23 and K-edge, Fluorescence yield L23M45 and L23M1, RIXS core valence and core core excitations, nIXS valence and core excitations, PES, corePES, IPES and XES) \\ **Tutorials** \\ {{ :workshop:heidelberg:october_2026:08_materials.zip | Many spectroscopy examples on NiO}} |**Hands-on tutorials** \\ Polarisation and experimental geometry using tensor formulations in XAS, RIXS and NIXS. \\ **Tutorials** \\ {{ :workshop:heidelberg:september_2024:06_wednesday_afternoon_lda_plus_mlft.zip | T.B.A.}} \\ |**Hands-on tutorials** \\ From DFT to many-body model calculations \\ **Tutorials** \\ {{ :workshop:heidelberg:september_2024:08_thursday_afternoon_polarization.zip | T.B.A. }} \\ | ::: |
|17:00 - ...| **Arrival** |Free evening program |Free evening program |**Poster session** \\ Time for the participants to present their own research.|Free evening program |:::|
===== Posters =====
Feel free to bring your poster on Monday morning and place it on one of the walls of our institute.
===== Table of contents =====
{{indexmenu>.#2|msort nsort}}