calque

Schools

HoW exciting! Hands-on Workshop on Excitations in Solids 2012

August 2, 2012 to August 8, 2012
Location : Humboldt Universitaet zu Berlin, Germany

Organisers

  • Pasquale Pavone (Humboldt Universität zu Berlin, Germany)
  • Claudia Draxl (Humboldt University Berlin, Germany)
  • Juergen Spitaler (Materials Center Leoben Forschung GmbH, Austria)
  • Hannah Meyner (Humboldt-Universität zu Berlin, Germany)

Supports

   CECAM

   Psi-k

Description

The main goal of this tutorial is to introduce young scientists to the theoretical 
foundations of state-of-the-art ab-initio techniques through keynote lectures given by 
world-leading experts. On the same occasion, young scientist will have the opportunity 
to put this knowledge into practice through hands-on exercises with the software package 
exciting based on density-functional theory (DFT). Therefore, exploring the fundamental 
physical concepts in combination with practical exercises also comprises the important 
pedagogical aspect of learning by doing. Each of the presented topic will be treated in 
a twofold way, first introducing the general concepts and, then, presenting applications 
to real materials. We will focus on the treatment of various excitations, crucial to 
understand and predict electronic, optical, and thermodynamic properties of materials. 
This is exactly the point where basic research meets the needs of industrial applications. 
The development of new theoretical and computational approaches requires a flexible 
organization of the program package as well as a developer-friendly environment. 
The codes must be able to handle reliably sophisticated implementations of theoretical 
concepts to allow for forefront basic research. At the same time, employing such codes 
for practical purposes by non-specialists in programming or DFT asks for well documented 
packages and a user-friendly environment. Only this way codes can be utilized in applied 
materials research, i.e., also by industries. exciting fulfills all these needs, and the 
program package covers a variety of tools for calculating and analyzing both ground-state 
properties and excitations in condensed matter. We wish to provide training on this 
package to the young generation of scientists and developers. 
Besides the fundamentals related to the method and hands-on exercises, we will provide 
keynote lectures given by world-leading experts in the various fields we want to focus on. 
They will comprise the cornerstones of DFT, time-dependent DFT (TDDFT), many-body 
perturbation theory (MBPT), linear response and phonons, superconductivity, 
the GW method, thermoelectricity, and the physics of carbon monolayers.
The outcome of this tutorial will be manifold: (i) Since exciting solves the Kohn-Sham 
equations very accurately and exhibits various unique features in terms of excited-state 
properties, exciting can be more and more utilized as a benchmark for other methods which 
make use of different approximations. (ii) Equipped with modern programming instruments 
(e.g., XML input and output, a series of scripts for automatizing the computation of various 
physical properties, and graphical analysis tools) exciting can be straightforwardly 
interfaced with other packages. Since we will invite keynote speakers from various areas, 
including experts in code-development, we also aim at confronting different techniques and 
fostering possible collaborations towards future code development. Hence, the trainees will 
have not only the chance to deeply work into the linearized augmented planewave (LAPW) 
method, but also can benefit from a honest comparison with other methods. (iii) Introducing 
the code to the young generation will contribute to its dissemination and future development.

LATEST NEWS:

Please notice that the deadline for free-of-charge participation is over. Participation to the tutorial is still possible. In this case, a conference fee of 200 Euro (including also lunches, excursion, coffee breaks, and social dinner) will be required.

The up-to-date workshop program can be downloaded either here in the Files section or at the exciting-code web site: http://exciting-code.org


The main goal of this tutorial is to introduce young scientists to the theoretical foundations of state-of-the-art first-principles techniques based on and going beyond densitiy-functional theory (DFT) through keynote lectures given by world-leading experts. On the same occasion, young scientist will have the opportunity to put this knowledge into practice through hands-on exercises with the software package.This CECAM workshop aims at providing training to young people, making them familiar with the exciting code (see web site: http://exciting-code.org).  

exciting is a young public-domain all-electron package based on DFT for the investigation of condensed matter on the atomic scale. It combines several major advantages: (i) It is a full-potential all-electron code based on the linearized augmented plane-wave (LAPW) method, which stands for highest precision and the fact that it can be used for any material. (ii) It is the only all-electron package comprising vast implementations of excited-state properties within TDDFT as well as many-body perturbation theory. (iii) It is developers-friendly through a clean and fully documented programming style, being written from scratch and handled with a modern version-control system (git). (iv) It is user-friendly through an easy-to-handle user interface comprising various tools to create and validate input files and analyze results. (v) It is seminal by being interfaced to packages operating on the next higher length scale and by the development of tools which allow for the handling by users from an industrial environment. Each of the presented topic will be treated in a twofold way: introducing the general concepts, as well as presenting applications to real materials. We will focus on the treatment of various excitations, crucial to understand and predict electronic, optical, and lattice-dynamical properties of materials.

We will provide keynote lectures given by world-leading experts in the various fields we want to focus on. They will comprise the cornerstones of DFT, time-dependent DFT (TDDFT), many-body perturbation theory (MBPT) for one- and two-body Green functions, and linear-response theory. Besides the fundamental theory, some presentations will be dedicated to cutting-edge applications such as thermoelectricity or the physics of carbon monolayers.

The typical session block of 1/2 a day will have the following structure:

  • Keynote lecture
  • Talk about LAPW-specific features and implementation within the exciting code
  • Hands-on exercise

We plan 11 session blocks, which results in a total of six and a half conference days, including one day for the conference excursion.

Tutorial topics

  • Density-functional theory: Introduction and advances
  • Linear response to lattice excitations: Theory and applications
  • The GW approach: Survey, limitations, challenges, and applications
  • The Bethe-Salpeter equation (BSE): Survey, limitations, challenges, and applications
  • Time-dependent DFT: Survey, limitations, challenges, and applications
  • Applications: From thermoelectrics to the physics of carbon monolayer
  • Challenges in large-scale computations

LAPW-specific talks

  • The family of APW methods
  • Structural optimization with exciting
  • ElaStic@exciting
  • Phonons@exciting
  • TDDFT@exciting
  • GW@exciting
  • BSE@exciting
  • Core-excitations@exciting
  • exciting input and output 
  • exciting templates & more

Hands-on exercises

  • Input/output and templating
  • Structure optimization
  • Kohn-Sham band structure and density of states
  • Elastic properties
  • Exchange-correlation functionals
  • Van-der-Waals interactions
  • Phonons and related properties
  • Quasi-partilce band structure from GW
  • Optical spectra and electron loss from TDDFT
  • Exciton spectra from BSE
  • Core excitations from BSE 
  • exciting@web

 

References

[1] J.P. Perdew, K. Burke, and M. Ernzerhof, Generalized gradient approximation made simple, Phys. Rev. Lett. 77, 3865 (1996)

[2] K. Burke and R. Magyar, ABC of DFT, http://dft.uci.edu/

[3] P. Giannozzi, S. de Gironcoli, P. Pavone, and S. Baroni, Ab-initio calculation of phonon dispersions in semiconductors, Phys. Rev. B 43, 7231 (1991)

[4] S. Baroni, S. de Gironcoli, A. Dal Corso, and P. Giannozzi, Phonons and related crystal properties from density-functional perturbation theory, Rev. Mod. Phys. 73, 515-562 (2001)

[5] S. Albrecht, L. Reining, R. Del Sole, and G. Onida, Ab initio calculation of excitonic effects in the optical spectra of semiconductors, Phys. Rev. Lett. 80, 4510 (1998)

[6] G. Onida, L. Reining, and A. Rubio, Electronic excitations: density-functional vs many-body Green's-function approaches, Rev. Mod. Phys. 74, 601 (2002)

[7] L.N. Oliveira, E.K.U. Gross, W. Kohn, Density-Functional Theory for Superconductors, Phys. Rev. Lett. 60, 2430 (1988)

[8] M.A.L. Marques and E.K.U. Gross, Time-Dependent Density-Functional Theory in "A Primer in Density Functional Theory", edited by C. Fiolhais, F. Nogueira, and M. Marques (Springer-Verlag, NY, 2003)

[9] M.S. Hybertsen and S.G. Louie, Electron correlation in semiconductors and insulators: Band gaps and quasiparticle energies, Phys. Rev. B 34, 5390 (1986)

[10] M.S. Hybertsen and S.G. Louie, First-Principles Theory of Quasiparticles: Calculation of Band Gaps in Semiconductors and Insulators, Phys. Rev. Lett. 55, 1418 (1985)

[11] J.O. Sofo, A.S. Chaudhari, and G.D. Barber, Graphane: A two-dimensional hydrocarbon, Phys. Rev. B 75, 153401 (2007)

[12] G.D. Mahan and J.O. Sofo, The best thermoelectric, Proc. Nat. Acad. Sci. U.S.A. 93, 7436 (1996)

[13] J.C. Grossman, E. Schwegler, E.W. Draeger, F. Gygi, and G. Galli, Towards an assessment of the accuracy of DFT for first principles simulations of water, J. Chem. Phys. 120, 300 (2004)