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Workshops

Electron-vibration coupling : theoretical and numerical challenges

May 27, 2015 to May 29, 2015
Location : CECAM-HQ-EPFL, Lausanne, Switzerland
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   Visa requirements

Organisers

  • Andrea Marini (National Research Council, Italy)
  • Xavier Gonze (Université Catholique de Louvain, Belgium)
  • Claudia Draxl (Humboldt University Berlin, Germany)

Supports

   CECAM

   Psi-k

Description

As it is clear from the state-of-the-art section, despite the enormous interest in the EV interaction and the very large basis of scientists involved, this research field is still fragmented in many different methods and approaches.

This is inevitably creating a gap between the theoretical and experimental communities. A gap that this workshop aims to tackle by discussing several key topics and ideas which will surely foster lively discussions.

Search of a systematic way to perform a perturbative treatment of the EV interaction in a pure ab-initio basis. This workshop is opened to theoreticians working both with ab-initio methods and with model Hamiltonians. Talks from both communities are scheduled for the first day. Those talks will be followed by a round-table where the very different approaches will be compared and discussed offering an unique opportunity for future developments.


Is a perturbative treatment of the EV interaction suitable and accurate? The theories based on model Hamiltonians are not perturbative but lack of an atomistic description. The theories based, instead, on DFT have a solid atomistic basis but are perturbative. This workshop can give the opportunity to find concrete ways to merge the atomistic description with the non-perturbative treatment.

What are the most relevant and recent achievements in the experimental community ?The session about spectroscopies will host talks by prominent experimentalists. The problems and perspectives opened by their results will be discussed and compared with the most recent theoretical and numerical advances in the field. This will offer an unique opportunity of assessing shortcomings and merits of both the theoretical and experimental point of view.

One of the most used and widely spread assumption is that the EV interaction can yield only minor corrections (of the order of meV) to the electronic levels. As a consequence the majority of the simulations of the electronic and optical properties of a wide class of materials are generally performed by keeping the atoms frozen in their crystallographic positions. This workshop will show clear theoretical and experimental proofs of the absolute importance of including the effects of the EV interaction in any basic theoretical and numerical scheme. The deep and daily discussions and the gathering of scientists belonging to very different research areas will boost such awareness.

Phonons are harmonic excitations and the harmonic approximation is known to be valid only for temperatures much lower than the Debye temperature. What happens above this temperature ? And are anharmonic corrections always negligible even at, for example, room temperature? The specific section dedicated to anharmonic effects will represent an excellent source of discussions.

Heat transport and thermoelectricity are advanced applications of the EV interaction. What can we learn from their methods? The specific section dedicated to Heat transport and thermoelectricity will, again, represent an excellent source of discussions.


For participants from US there is the possibility to apply for an NSF funded travel award program. For more informations visit http://mcc.illinois.edu/travel/

References

1. Allen, Cardona, Phys.Rev.B 27, 4760 (1983), and refs therein
2. Gosar, Choi, Phys.Rev. 150, 529 (1966).
3. Heeger, et al. Rev.Mod.Phys.60, 781 (1988)
4. Vukmirovic, Bruder, Stojanovic, Phys.Rev.Lett. 109, 126407 (2012)
5. Xu, Verstraete, Phys.Rev.Lett.112, 196693 (2014), and refs therein
6. Attaccalite, et al, NanoLetters 10, 1172 (2010).
7. Gillet, Giantomassi, Gonze, Phys.Rev.B88, 094305 (2013)
8. Noffsinger, et al, Phys.Rev.Lett. 108, 167402 (2012)
9. Schrieffer, Theory of Superconductivity, Perseus Books, 1999
10. Antonius et al, Phys.Rev.Lett. 112, 215501 (2014) and refs therein.
11. Onida, et al. Rev.Mod.Phys.74, 601 (2002)
12. Eiguren, Ambrosch-Draxl, Phys.Rev.Lett.101, 036402 (2008)
13. Capaz et al Phys.Rev.Lett.94, 036801 (2005)
14. Marini, Phys.Rev.Lett.101, 106405 (2008)
15. Giustino, et al. Phys.Rev.Lett.105, 265501 (2010)
16. Cannuccia, Marini, Phys.Rev.Lett. 107, 255501 (2011)
17. Moser et al, Phys.Rev.Lett.110, 196403 (2013)