Atomistic Green’s Functions: The Beauty of Self-energies

By Tillmann Christoph Kubis

Electrical and Computer Engineering, Purdue University, West Lafayette, IN

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Abstract

The value of nonequilibrium Green's function (NEGF) implementations stands and falls with the quality of its self-energies. This presentation gives an introduction to NEGF. It will be explained how self-energies cause NEGF to fundamentally differ from most other quantum methods. Atomistic examples of phonon and impurity scattering self-energies agree quantitatively with experiments. The latest development in NEGF, the ROBIN method, overcomes notorious shortcomings of periodic boundary conditions in defect and disordered material simulations.

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Researchers should cite this work as follows:

  • Tillmann Christoph Kubis (2020), "Atomistic Green’s Functions: The Beauty of Self-energies," https://nanohub.org/resources/34220.

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Atomistic Green’s Functions: The Beauty of Self-energies
  • Atomistic Green's functions: the beauty of self-energies 1. Atomistic Green's functions: t… 0
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  • Highlight: Impact of periodicity assumption 2. Highlight: Impact of periodici… 24.758091424758092
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  • This presentation 3. This presentation 146.31297964631298
    00:00/00:00
  • Nonequilibrium Green's functions (NEGF) 4. Nonequilibrium Green's functio… 182.38238238238239
    00:00/00:00
  • 2 aspects of stationary NEGF 5. 2 aspects of stationary NEGF 223.15648982315651
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  • NEGF and self-energies Ʃ 6. NEGF and self-energies Ʃ 334.96830163496833
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  • Retarded self-energies: shifting resonances 7. Retarded self-energies: shifti… 363.93059726393062
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  • Example for electron-phonon self-energy 8. Example for electron-phonon se… 440.57390724057393
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  • NEGF – Scattering in polar 3D materials 9. NEGF – Scattering in polar 3… 489.15582248915587
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  • Verification of scattering self-energies 10. Verification of scattering sel… 498.66533199866535
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  • Verification of scattering self-energies 11. Verification of scattering sel… 608.008008008008
    00:00/00:00
  • Band gap narrowing parameter extraction 12. Band gap narrowing parameter e… 646.04604604604606
    00:00/00:00
  • BGN: Comparison with experimental data 13. BGN: Comparison with experimen… 703.57023690357028
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  • Urbach parameter extraction 14. Urbach parameter extraction 721.05438772105447
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  • Urbach parameter: NEGF vs. experiments 15. Urbach parameter: NEGF vs. exp… 752.88621955288625
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  • NEGF – Scattering in transition metal dichalcogenides 16. NEGF – Scattering in transit… 780.04671338004675
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  • Role of scattering in TMDs 17. Role of scattering in TMDs 792.72605939272614
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  • Maximally localized Wannier functions in NEMO5 18. Maximally localized Wannier fu… 850.45045045045049
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  • Transition metal dichalcogenides – 2D 19. Transition metal dichalcogenid… 884.0173506840174
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  • 2D systems: NEGF vs. experiments 20. 2D systems: NEGF vs. experimen… 930.09676343009676
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  • Impact of remote phonon scattering 21. Impact of remote phonon scatte… 959.79312645979314
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  • NEGF – door opener to model irregular systems 22. NEGF – door opener to model … 1025.5255255255256
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  • General iterative lead contact self-energy 23. General iterative lead contact… 1037.9713046379713
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  • Method origins: method for irregular leads 24. Method origins: method for irr… 1070.1034367701034
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  • ROBIN method verification 25. ROBIN method verification 1146.8134801468136
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  • Results: graphene + periodic Si doping 26. Results: graphene + periodic S… 1198.9656322989656
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  • Results: graphene + periodic Si doping 27. Results: graphene + periodic S… 1314.647981314648
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  • Results: graphene + random Si doping 28. Results: graphene + random Si … 1383.883883883884
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  • Generality of ROBIN 29. Generality of ROBIN 1500.1668335001668
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  • Conclusion 30. Conclusion 1548.1147814481149
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