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We present the implementation of spinor quantum transport within the non-equilibrium Green's function (NEGF) code TranSIESTA based on Density Functional Theory (DFT). First-principles methods play an essential role in molecular and material…

Mesoscale and Nanoscale Physics · Physics 2025-06-02 Nils Wittemeier , Nick Papior , Mads Brandbyge , Zeila Zanolli , Pablo Ordejón

This review deals with the nonequilibrium Green's function (NEGF) method applied to the problems of energy transport due to atomic vibrations (phonons), primarily for small junction systems. We present a pedagogical introduction to the…

Mesoscale and Nanoscale Physics · Physics 2013-05-28 Jian-Sheng Wang , Bijay Kumar Agarwalla , Huanan Li , Juzar Thingna

Simulations of quantum transport in coherent conductors have evolved into mature techniques that are used in fields of physics ranging from electrical engineering to quantum nanoelectronics and material science. The most efficient…

Mesoscale and Nanoscale Physics · Physics 2019-12-25 Mathieu Istas , Christoph Groth , Xavier Waintal

We report the capability to simulate in a quantum mechanical tight-binding (TB) atomistic fashion NW devices featuring several hundred to millions of atoms and diameter up to 18 nm. Such simulations go far beyond what is typically…

Mesoscale and Nanoscale Physics · Physics 2021-02-05 Aryan Afzalian , Tim Vasen , Peter Ramvall , Matthias Passlack

Real-time time-dependent density functional theory (rt-TDDFT) with hybrid exchange-correlation functional has wide-ranging applications in chemistry and material science simulations. However, it can be thousands of times more expensive than…

Computational Physics · Physics 2019-05-07 Weile Jia , Lin-Wang Wang , Lin Lin

Efficient simulation of quantum circuits has become indispensable with the rapid development of quantum hardware. The primary simulation methods are based on state vectors and tensor networks. As the number of qubits and quantum gates grows…

Quantum Physics · Physics 2024-08-13 Feng Pan , Hanfeng Gu , Lvlin Kuang , Bing Liu , Pan Zhang

We implement, optimize, and validate the linear-scaling Kubo-Greenwood quantum transport simulation on graphics processing units by examining resonant scattering in graphene. We consider two practical representations of the Kubo-Greenwood…

Mesoscale and Nanoscale Physics · Physics 2014-02-14 Zheyong Fan , Andreas Uppstu , Topi Siro , Ari Harju

III-V tunneling field-effect transistors (TFETs) offer great potentials in future low-power electronics application due to their steep subthreshold slope and large "on" current. Their 3D quantum transport study using non-equilibrium Green's…

Mesoscale and Nanoscale Physics · Physics 2016-10-04 Jun Z. Huang , Lining Zhang , Pengyu Long , Michael Povolotskyi , Gerhard Klimeck

An efficient implementation of the nonequilibrium Green function (NEGF) method combined with the density functional theory (DFT) using localized pseudo-atomic orbitals (PAOs) is presented for electronic transport calculations of a system…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 Taisuke Ozaki , Kengo Nishio , Hiori Kino

We present novel methods implemented within the non-equilibrium Green function code (NEGF) transiesta based on density functional theory (DFT). Our flexible, next-generation DFT-NEGF code handles devices with one or multiple electrodes…

Mesoscale and Nanoscale Physics · Physics 2016-12-30 Nick Papior , Nicolás Lorente , Thomas Frederiksen , Alberto García , Mads Brandbyge

Time-dependent quantum transport for graphene nanoribbons (GNR) are calculated by the hierarchical equation of motion (HEOM) method based on the nonequilibrium Green's function (NEGF) theory (Xie et.al, J. Chem. Phys. 137, 044113, 2012). In…

Mesoscale and Nanoscale Physics · Physics 2013-04-02 Hang Xie , Yanho Kwok , Yu Zhang , Feng Jiang , Xiao Zheng , YiJing Yan , GuanHua Chen

Classical simulation of quantum circuits remains indispensable for algorithm development, hardware validation, and error analysis in the noisy intermediate-scale quantum (NISQ) era. However, state-vector simulation faces exponential memory…

Based on the non-equilibrium Green's function (NEGF) coupled with density function theory (DFT), namely, NEGF-DFT quantum transport theory, we propose an efficient formalism to calculate the transient current of molecular devices under a…

Mesoscale and Nanoscale Physics · Physics 2015-06-12 L. Zhang , J. Chen , J. Wang

We discuss the calculation of the carrier mobility in silicon films within the quantum Non-Equilibrium Green's Functions (NEGF) framework. We introduce a new method for the extraction of the carrier mobility that is free from contact…

Mesoscale and Nanoscale Physics · Physics 2014-02-14 Yann-Michel Niquet , Viet-Hung Nguyen , François Triozon , Ivan Duchemin , Olivier Nier , Denis Rideau

Non-equilibrium electronic quantum transport is crucial for the operation of existing and envisioned electronic, optoelectronic, and spintronic devices. The ultimate goal of encompassing atomistic to mesoscopic length scales in the same…

Computational Physics · Physics 2024-10-08 Saurabh Sawant , François Léonard , Zhi Yao , Andrew Nonaka

With the continued scaling of microelectronic devices along with the growing demand of high-speed wireless telecommunications technologies, there is increasing need for high-frequency device modeling techniques that accurately capture the…

Mesoscale and Nanoscale Physics · Physics 2018-05-29 Timothy M. Philip , Matthew J. Gilbert

To find deterministic solutions to the transient $S_N$ neutron transport equation, iterative schemes are typically used to treat the scattering (and fission) source terms. We explore the one-cell inversion iteration scheme to do this on the…

Computational Physics · Physics 2023-08-10 J. P. Morgan , Ilham Variansyah , Todd S. Palmer , Kyle E. Niemeyer

The dynamics of a closed quantum system is often studied with the direct evolution of the Schrodinger equation. In this paper, we propose that the gauge choice (i.e. degrees of freedom irrelevant to physical observables) of the Schrodinger…

Numerical Analysis · Mathematics 2020-02-20 Dong An , Lin Lin

Many-particle continuous-time quantum walks (CTQWs) represent a resource for several tasks in quantum technology, including quantum search algorithms and universal quantum computation. In order to design and implement CTQWs in a realistic…

Quantum Physics · Physics 2017-10-02 Enrico Piccinini , Claudia Benedetti , Ilaria Siloi , Matteo G. A. Paris , Paolo Bordone

With the technical progress of radio-frequency setups, high frequency quantum transport experiments have moved from theory to the lab. So far the standard theoretical approach used to treat such problems numerically--known as Keldysh or…

Mesoscale and Nanoscale Physics · Physics 2014-08-26 Benoit Gaury , Joseph Weston , Christoph Groth , Xavier Waintal