IWCN 2021: How to Preserve the Kramers-Kronig Relation in Inelastic Atomistic Quantum Transport Calculations
15 Jul 2021 | Online Presentations | Contributor(s): Daniel Alberto Lemus, James Charles, Tillmann Christoph Kubis
The nonequilibrium Green’s function method (NEGF) is often used to predict quantum transport in atomically resolved nanodevices. This yields a high numerical load when inelastic scattering is included. Atomistic NEGF had been regularly applied on nanodevices, such as nanotransistors....
IWCN 2021: Density Functional Theory Modeling of Chemical Reactions at Interfaces
15 Jul 2021 | Online Presentations | Contributor(s): Namita Narendra, Jessica Wang, James Charles, Tillmann Christoph Kubis
In this work, we introduce a DFT-based method to predict energies of solute molecules in bulk solution and in various distances to solvent/air interfaces. The solute and all solvent molecules (~1400 atoms) are explicitly considered, and their electrons solved self-consistently in density...
IWCN 2021: Recursive Open Boundary and Interfaces Method for Material Property Predictions
14 Jul 2021 | Online Presentations | Contributor(s): James Charles, Sabre Kais, Tillmann Christoph Kubis
In this presentation, we show that assuming periodicity elevates a small perturbation of a periodic cell into a strong impact on the material property prediction. Periodic boundary conditions can be applied on truly periodic systems only. More general systems should apply an open boundary...
Atomistic Green’s Functions: The Beauty of Self-energies
28 Oct 2020 | Online Presentations | Contributor(s): Tillmann Christoph Kubis
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.
Nonequilibrium Green's Functions: Reliably Predicting Chemical Reactions
07 Mar 2017 | Online Presentations | Contributor(s): Tillmann Christoph Kubis
In this talk, an introductory overview of the nonequilibrium Green’s function (NEGF) method will be given. NEGF results in state-of the art semiconductor nanodevices will illustrate the strengths of the method. Unique benefits of the method for molecular chemistry will be highlighted...
Transferable Tight Binding Model for Strained Heterostructures
22 Oct 2016 | Online Presentations | Contributor(s): Yaohua Tan, Michael Povolotskyi, Tillmann Christoph Kubis, Timothy Boykin, Gerhard Klimeck
IWCE 2015 presentation.
NEMO5 and 2D Materials: Tuning Bandstructures, Wave Functions and Electrostatic Screening
19 Oct 2016 | Online Presentations | Contributor(s): Tillmann Christoph Kubis
In this talk, I will briefly discuss the MLWF approach and compare it to DFT and atomistic tight binding. Initial results using the MLWF approach for 2D material based devices will be discussed and compared to experiments. These results unveil systematic band structure changes as functions of the...
Self-energies: Opening Doors for Nanotechnology
07 Apr 2016 | Online Presentations | Contributor(s): Tillmann Christoph Kubis
In this talk, it will be shown how the concept of self-energies can be used to interface all these fields into the same nanotechnology modeling framework. Self-energies are most commonly used in the quantum transport method of nonequilibrium Green’s functions (NEGF). The NEGF method is...
Mode Space Tight Binding Model for Ultra-Fast Simulations of III-V Nanowire MOSFETs and Heterojunction TFETs
13 Nov 2015 | Online Presentations | Contributor(s): Aryan Afzalian, Jun Huang, Hesameddin Ilatikhameneh, Santiago Alonso Perez Rubiano, Tillmann Christoph Kubis, Michael Povolotskyi, Gerhard Klimeck
IWCE 2015 presentation. we explore here the suitability of a mode space tight binding algorithm to various iii-v homo- and heterojunction nanowire devices. we show that in iii-v materials, the number of unphysical modes to eliminate is very high compared to the si case previously reported...
NEMO5: Why must we treat topological insulator nanowires atomically?
15 Oct 2015 | Online Presentations | Contributor(s): Fan Chen, Michael J. Manfra, Gerhard Klimeck, Tillmann Christoph Kubis
IWCE 2015 presentation. Abstract and more information to be added at a later date.
NEMO5 Tutorial 6A: Device Simulation - Transport (Double Gate)
18 Jul 2012 | Online Presentations | Contributor(s): Mehdi Salmani Jelodar, Seung Hyun Park, Zhengping Jiang, Tillmann Christoph Kubis, Michael Povolotskyi, Gerhard Klimeck
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NEMO5 Overview Presentation
17 Jul 2012 | Online Presentations | Contributor(s): Tillmann Christoph Kubis, Michael Povolotskyi, Jean Michel D Sellier, James Fonseca, Gerhard Klimeck
This presentation gives an overview of the current functionality of NEMO5.
Nonequilibrium Green’s functions theory: Transport and optical gain in THz quantum cascade lasers
26 Mar 2010 | Online Presentations | Contributor(s): Tillmann Christoph Kubis
Quantum cascade lasers (QCLs) are promising sources of coherent THz radiation. However, state of the art THz-QCLs are still limited to cryogenic temperatures. The charge transport in these QCLs is subject to coherent quantum phenomena, such as quantum tunneling, confinement and interferences as...