nextnano.NEGF - Software for
Quantum Transport qcl

qcl:advanced_settings

2022-03-30T16:36:50+00:00

Parallelization Number of threads The number of threads can be controlled using the command ... 12 ... For an automatic setting, use 0 or do not specify this command. In this case, the number of threads will be set to half of the number of physical cores.

qcl:electronic_band_structure

2022-07-23T17:22:53+00:00

The band structure is modeled in the envelope function approximation, using either the single-band effective mass approximation or a multiband model. To describe non-parabolicity, 2- or 3-band models are needed. The 3-band modeled is strongly recommended for structures based on electrons in III-V heterostructures.

qcl:faq

2022-10-12T09:27:12+00:00

Can you recommend some reading material on the background of the NEGF method? For a first reading on NEGF, there are several good introductions published by Supriyo Datta. Other books or articles on NEGF usually require advanced quantum mechanics or quantum field theory.

qcl:general_remarks

2020-06-09T13:11:06+00:00

nextnano.NEGF is a console application that is run from within the nextnanomat software (GUI). Alternatively, it can be executed from the command line. The input file specifies the device that shall be simulated. nextnanomat nextnanomat is a convenient graphical user interface for nextnano.NEGF. It is included in the nextnano.NEGF package, and can also be downloaded from here. It can visualize 1D, 2D and 3D simulations results.

qcl:input_file

2023-01-05T10:07:56+00:00

The structure to be simulated as well as all simulation parameters have to be specified in an XML file which can be edited by the users. The contents of such a file are described in the following. More advanced and optional features are also described in the advanced_settings page.

qcl:linux

2020-11-27T14:10:08+00:00

nextnano.NEGF on Linux nextnano.NEGF can be executed on Linux using the Wine compatibility layer. See below for the installation intstructions for several Linux distrubutions. Using nextnano.NEGF with Wine After having downloaded the nextnano.NEGF zip file from https://www.nextnano.com/nextnano3/restricted/download/update/nextnano.NEGF.zip, please extract it to your preferred path. Having access to the material database Material_Database.xml and the license file License_nnQCL.lic, one can run…

qcl:list_of_updates

2020-11-20T14:38:45+00:00

Photon-assisted transport and gain clamping are now supported to simulate lasing above threshold and quantum cascade detectors. This new feature is illustrated in the sample files “MidIR_QCL_InGaAs_InAlAs_Bai_APL2011_GainClamping_12subbbands.xml“ (faster) and “MidIR_QCL_InGaAs_InAlAs_Bai_APL2011_GainClamping_21subbbands.xml” (more accurate) where LIV curves are calculated. The corresponding documentation can be found here: Photon-assisted transport and gain clamping

qcl:material_database

2021-01-04T15:04:08+00:00

Material database The default material parameters are stored in a database file called Material_Database.xml. This default material database can be open in the nextnanomat GUI though: File => Open nextnano.NEGF Default Database If you run nextnano.NEGF via the nextnanomat GUI, you can choose to read in a customized material database as follows:

qcl:nextnano.qcl_documentation

2020-06-19T09:46:30+00:00

* The nextnano.QCL software - Summary and introduction * Tutorials * General remarks * Input file * Simulation output * Material database * FAQ (Frequently asked questions) * Feature requests

qcl:optics

2023-07-05T08:36:02+00:00

There are two different kind of gain/absorption calculations which is given by nextnano.NEGF: * the semiclassical one, which uses the populations and the linewidths calculated from the NEGF steady-state solution to calculate the gain/absorption in a semiclassical way; * the “self-consistent” one, fully calculated using the NEGF formalism . In this case, linear response theory to an a.c. incoming field is considered, and time-dependent Green's functions are used.

qcl:photon-assisted_transport_and_gain_clamping

2022-03-30T17:19:07+00:00

Photon-assisted transport and gain clamping Photon-assisted transport Photon-assisted transport can be modeled by considering electromagnetic (EM) modes at specific energies. 253.0

qcl:publications_using_nextnano.negf

2022-08-28T10:34:24+00:00

* Theoretical Study of Quasi One-Well Terahertz Quantum Cascade Laser Boyu Wen, Dayan Ban Photonics 9, 247 (2022) * Analyses of Optical Gains and Oscillation Wavelengths for Quantum Cascade Lasers Using the Nonequilibrium Green’s Function Method Hirotaka TANIMURA, Shigeyuki TAKAGI, Tsutomu KAKUNO, Rei HASHIMOTO, Kei KANEKO, Shinji SAITO J. Comput. Chem. Jpn. Int. Ed., Vol. (2022)

qcl:simulation_of_resonant_tunneling_diodes_rtds

2022-03-30T17:13:14+00:00

The following page (in construction) describes the simulation of devices with open boundary conditions such as RTDs with the nextnano.NEGF software. Note that in the current version (2022-03-30), only single band calculations are supported for open boundary conditions. A multiband version is currently developed.

qcl:simulation_output

2022-09-20T17:10:47+00:00

For each simulation run, a new output folder is created in the simulation output folder. The created folder has the name of the input file. In addition, date-time can be added to the folder name by the nextnanomat setting (Tools -> Options -> Expert settings before Aug 2021, Tools -> Options -> View/Output since Aug 2021). For nextnanomat before Aug 2021, this option is recommended in order to avoid overwriting existing output data. For nextnanomat after Aug 2021, simulation output is per defau…

qcl:software_documentation

2017-07-24T12:51:55+00:00

nextnano.QCL - General remarks nextnano.QCL is a console application that is run from within the nextnanomat software (GUI). Alternatively, it can be executed from the command line. The input file specifies the device that shall be simulated. nextnanomat nextnanomat is a convenient graphical user interface for nextnano.QCL. It can be downloaded from here. It can visualize 1D, 2D and 3D simulations results.

qcl:sweeping_variables

2020-06-09T13:12:13+00:00

The nextnanomat graphical user interface allows to sweep any variable of the nextnano.NEGF input file. Algebraic expressions are also supported. First, the variable to be swept has to be declared in the input file: $Lcorrel 5

qcl:the_nextnano.qcl_software

2020-07-03T13:56:11+00:00

Moved to

qcl:tutorials

2022-02-17T13:05:39+00:00

Tutorials Here we describe several example input files. THz QCLs GaAs/AlGaAs * THz QCL - Fathololoumi (2012) Terahertz quantum cascade lasers operating up to ~200 K with optimized oscillator strength and improved injection tunneling S. Fathololoumi, E. Dupont, C.W.I. Chan, Z.R. Wasilewski, S.R. Laframboise, D. Ban, A. Mátyás, C. Jirauschek, Q. Hu, H. C. Liu Optics Express 20, 3866 (2012)

qcl:updates

2017-07-31T13:14:27+00:00

qcl:working_principle

2018-07-16T11:36:13+00:00

The code is based on the non-equilibrium Green's functions (NEGF) formalism (also known as the Keldysh, or Kadanoff-Baym formalism). This formalism allows to account for both quantum transport effects (i.e. coherent transport effects, such as resonant tunneling), as well as scattering mechanisms.

nextnano.NEGF - Software for Quantum Transport qcl