Theory of spectroscopy, dynamics and numerical methods for complex materials


Winter semester 2017 / 2018 - Condensed Matter Theory I

link to website of lecture:

Summer semester 2017 - Condensed Matter Theory

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Summer semester 2017 - Computational methods in Solid state physics

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Summer semester 2017 - Oberseminar Physik komplexer Systeme

Introduction to quantum dynamics in atoms, molecules and solids - Heidelberg graduate days 10-13 April 2017

The binding of an Oxygen atom in a red blood-cell, the ultrafast switching of magnetic domains in your hard disk or the Catalytic reaction of nitrogen to ammonia in the vicinity of iron oxides all require the understanding of the electronic dynamics on the quantum scale. With the recent advance of experimental methods aimed to visualize these dynamical processes there is a need for theory that can describe quantum dynamics in atoms molecules and solids governing many orders of magnitude in time scales, from atto seconds to days. Although a full quantitative prediction of the three aforementioned processes is still out of reach using a combination of different theories and approximations we can get quite a good description in many cases.

In these lectures we will introduce some concepts of electron dynamics. Exemplified by several model calculations (and take home examples) we will show how the dynamics on the quantum scale can be described in solid state materials. We will draw parallels between the classical and quantum regime when possible. Our main starting point will be response theory showing the relation between excitation spectra and dynamics. We will introduce concepts like (natural) line-width of an excitation and how the related quasiparticle will decay once excited.

Response functions: spectroscopy and dynamics

X-ray spectroscopy - summer school lecture

Available on Itunes UXSS, Stanford Hercules, Grenoble

A 1 1/2 hour lecture introducing the basics of various core level spectroscopies (XAS, RXD, RIXS) on transition metal compounds. The lecture starts by introducing (correlated) transition metal compounds, why they are interesting, what are the open questions and how one can use core level spectroscopy to gain more insight into these materials and their physical properties. The lecture focusses on the relation between x-ray absorption (XAS), resonant elastic x-ray diffraction (RXD) and resonant inelastic x-ray scattering (RIXS). In the first half the basis properties of XAS are discussed, introducing the optical selection rules and the difference between band/continuum excitations and excitons. It is briefly discussed how one can calculate XAS spectra, as well as the sum-rules relating the integrated intensity to ground-state expectation values. Polarization dependence is discussed by introducing the optical conductivity tensor (at x-ray frequencies), which then can be naturally extended to the scattering tensor. Dynamical effects in diffraction are discussed. The lecture ends with a discussion of resonant inelastic x-ray scattering.

Hercules 2015 [76.1 Mb]
Success les Houches 2014 day 1 [26.43 Mb]
Success les Houches 2014 day 2 [49.75 Mb]
Success les Houches 2017 part 1 [32.7 Mb]
Success les Houches 2017 part 2 [57.8 Mb]

Introduction to spin-orbit coupling - summer school lecture

Two lectures of 1 hour introducing spin-orbit coupling in solids. Starting from Dirac equations the relevant relativistic interactions are discussed. Spin-orbit coupling in atoms is treated, including g-factors, magnetic moments and magnetic susceptibility. Next the spin-orbit interaction in a crystal-field picture is introduced including the effective angular momentum of the t2g sub shell. In the final part this is used to create a tight binding Hamiltonian which can describe Rashba splitting and topological states of mater.

Spin Orbit 2014 [85.19 Mb]