Electron-phonon coupling: Computational methods for electronic transport in nanostructures and in bulk materials
Location : CECAM-Lugano, Lugano, Switzerland
October 14, 2019 – October 16, 2019
Real-life performance of semiconductors and metals, whether it being in one, two, or three dimensions, is often limited by carrier scattering by phonons. The mobility of charge is a key parameter in the semiconductor industry to describe the electrical performance and the movement under applied electric fields. The traditional approach to calculate phonon-limited mobilities is based on the Boltzmann transport equation in combination with the effective mass approximation and empirical deformation potentials. Recently, predictive parameter-free mobility calculations have been carried out at the density functional theory (DFT) level for the electron-phonon coupling (EPC) [1-6].
EPC may also lead to a Bose-Einstein condensation of electrons near the Fermi surface as Cooper pairs, resulting in conventional superconductivity at sufficiently low temperatures. Also here DFT calculations of EPC have explained the origin of superconductivity in a range of materials and provided quantitative estimates for the critical temperature using Migdal-Eliashberg theory [7-8]. A recent example includes first-principles theory that revealed how high-pressure hydrogen sulfide is a strongly anharmonic superconductor .
In a different context, the introduction of Inelastic Electron Tunneling Spectroscopy together with STM/AFM scanning probe techniques have opened up the possibility to study adsorbates with unprecedented resolution and to characterize inelastic scattering against vibrations down to the single-molecule limit. Ab-initio approaches based on DFT and nonequilibrium Green’s functions (NEGF) have been developed to describe the EPC in such nanoscale junctions and to explain the inelastic transport characteristics [10-12].
Despite the common origin of EPC in these three distinct phenomena (phonon-limited resistivity, phonon-mediated superconductivity and IETS) the systems have traditionally been considered separately by different researchers and with different ab initio methods. In this workshop we propose to convene researchers interested in such EPC physics with the view to foster exchange between people with different approaches and methods.
Some key questions for the discussions would be:
· Ab-initio modelling of EPC in 3D materials: How to deal with the computational complexities of very large systems, such as explicit systems with explicit dopants, layered heterostructures, or organic molecular compounds?
. What are the advantages and limitations of currently available calculational schemes? How can scalability issues and applications to novel materials be addressed?
. Harmonic theory is often applied, but what are the impacts and signatures of anharmonicity in EPC in the derived phenomena (resistivity, superconductivity and IETS)?
. Prospects for a first-principles theory of driven BCS superconductivity?
· Beyond the Boltzmann approach: What can NEGF offer for mobility calculations? Which systems would be prone to interference effects that are beyond a semiclassical description? How to address the high-bias regime?
. How can existing ab initio IETS theory be developed further to describe interfaces and excitation of delocalized phonons?
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Matthieu Verstraete (invited speaker) (Universite de Liege)
Alexandre Reily Rocha (invited speaker) (Universidade Federal do ABC, Brazil)
Wu Li (invited speaker) (Institute for Advanced Study, Shenzhen University)
Pavel Jelinek (invited speaker) (Institute of Physics CAS)
Mads Brandbyge (invited speaker) (Technical University of Denmark, Lyngby)
Kristen Kaasbjerg (invited speaker) (CAMD, Technical University of Denmark)
Gemma Solomon (invited speaker) (University of Copenhagen)
Matteo Calandra (invited speaker) (Sorbonne Université)
Jelena Sjakste (Laboratoire des Solides Irradies, CNRS, Ecole Polytechnique)
Claudia Draxl (invited speaker) (Humboldt University Berlin)
Frank Ortmann (invited speaker) (Dresden University of Technology)
Dinesh Yadav (University of Konstanz)
Tim Wehling (invited speaker) (University of Bremen)
Stefano Sanvito (UCD, Dublin)
Ivana Savic (invited speaker) (Tyndall Natl. Institute)
Emi Minamitani (invited speaker) (Graduate School of Engineering, University of Tokyo)
Fabian Pauly (invited speaker) (Okinawa Institute of Science and Technology)
Ion Errea (invited speaker) (University of the Basque Country)
Bo Hellsing (invited speaker) (Gotheburg University)
Thibault Sohier (invited speaker) (EPFL)
Sven Reichardt (invited speaker) (University of Oxford)
Christopher McCooey (Queen’s University Belfast)
Samuel Poncé (invited speaker) (University of Oxford)
Day 1 – Monday October 14, 2019
08:30 to 08:50 Registration
08:50 to 09:00 Welcome
09:00 to 09:45 Matteo Calandra (CNR and Sorbonne Université, Paris, France)
Anharmonic melting of wharge density wave in single layer TiSe2
09:45 to 10:30 Matthieu Verstraete (University of Liege, Belgium)
Ab initio exciton and phonon dynamics in Transition Metal Dichalcogenides
10:30 to 11:00 Coffee Break
11:00 to 11:45 Mads Brandbyge (Dept. of Physics – Technical University of Denmark)
Large scale at low cost: Electron transport with electron-phonon coupling
11:45 to 12:30 Pavel Jelinek (Institute of Physics, Prague, Czech Republic)
Electron-phonon interaction in 1D molecular chains
12:30 to 13:15 Alexandre Reily Rocha (IFT- Sao Paulo State University, Brazil)
Structural and vibrational properties of water on the surface of a metal: out-of-equilibrium effects
13: 15 to 14:45 Lunch
14:45 to 15:30 Thibault Sohier (Theory and Simulation of Materials (THEOS), and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne, Switzerland)
Electronic transport workflow and high-throughput search for high-mobility 2D materials
15:30 to 16:15 Kristen Kaasbjerg (CAMD, Technical University of Denmark, Denmark)
First-principles modeling of disordered 2D materials
16:15 to 17:15 Discussion
17:15 to 17:45 Coffee Break
17:45 to 20:45 Poster Session
Day 2 – Tuesday October 15, 2019
08:30 to 09:15 Hellsing Bo (Dept. of Physics, Gothenburg University, Sweden)
Electron-phonon coupling in graphene – Linewidths of σ and π bands
09:15 to 10:00 Asier Eiguren (Condensed Matter Physics Dept. Uni. Basque Country (UPV/EHU), Spain and Donostia International Physics Center (DIPC), San Sebastian, Spain)
Efficient calculation electron-phonon related problems thought Helmholtz Fermi Surface harmonics (HFSH)
10:00 to 10:30 Coffee Break
10:30 to 11:15 Samuel Poncé (University of Oxford, United Kingdom)
Predictive calculations of phonon-limited carrier mobilities in semiconductors
11:15 to 12:00 Tim Wehling (University of Bremen, Germany)
Ab-initio phonon self-energies and fluctuation diagnostics of phonon anomalies
12:00 to 12:45 Raffaello Bianco (Centro de Física de Materiales (CSIC-UPV/EHU), Spain)
High-temperature superconducting hydrides: the crucial role of quantum anharmonic effects
12:45 to 14:15 Lunch
14:15 to 15:00 Sven Reichardt (University of Oxford, United Kingdom)
First-principles theory of electronic transport beyond the semi-classical Boltzmann equation
15:00 to 15:45 Ivana Savic (Tyndall National Institute, Cork, Ireland)
Simple and accurate Boltzmann transport approach to electronic transport in semiconductors from first principles
15:45 to 16:45 Discussion
16:45 to 17:15 Coffee Break
17:15 to 18:00 Fabian Pauly (Okinawa Institute of Science and Technology, Japan)
Photocarrier thermalization and inelastic effects in quantum transport through nanocontacts
18:00 to 18:45 Wu Li (Institute for Advanced Study, Shenzhen University, China)
Phonon-limited electronic transport and electron-dominated phonon transport from first principles
20:00 to 22:00 Social Dinner
Day 3 – Wednesday October 16, 2019
08:30 to 09:15 Frank Ortmann (Dresden University of Technology, Germany)
Vibrations and their Impact on Electronic and Transport Properties of Organic Materials
09:15 to 10:00 Gemma Solomon (University of Copenhagen, Denmark)
Quantum interference and inelastic transport in molecular junctions
10:00 to 10:30 Coffee Break
10:30 to 11:15 Emi Minamitani (Institute for Molecular Science, Japan)
Ab-initio simulation of phonon related transport phenomena: inelastic electron tunneling spectroscopy & thermal conductivity
11:15 to 12:00 Stefano Sanvito (School of Physics and CRANN, Trinity College Dublin, Ireland)
How do phonons relax molecular spins?
12:00 to 13:00 Discussion
The booklet is available here