Mailman 3 October 2024 - Kwant-discuss

conservation_law and particle_hole in finite systems
by Konner Feldman Dec. 14, 2024

Dec. 14, 2024

I am trying to simulate a finite size rectangular 2d electron gas inside a josephson junction. There is one rectangular scattering region on each end that is coupled to a different superconductor, while the middle rectangular scattering region is just a part of the semiconductor 2DEG. I am only simulating the 2DEG and not the superconductors, but there is still spin-orbit coupling and hole interactions. I was told that the "conservation_law" and "particle_hole” parameters are not needed for systems such as this one that do not have infinite length regions, but I don't understand why. Could somebody please help me understand this?

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Could not run codes from tkwant examples.
by jy2ff＠virginia.edu Oct. 29, 2024

Oct. 29, 2024

Hi, I have installed both Kwant and tkwant, and I had no problem running any tutotial codes from Kwant docmentation. However, when I tried to run some simple examples from tkwant documentation, an error pops up saying "The kernel appears to have died. It will restart automatically". Could you please explain this and help me fix it? Thanks in advance. Jian-Guang

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Couldn't install tkwant with python version 3.12
by jy2ff＠virginia.edu Oct. 24, 2024

Oct. 24, 2024

Hi, I have installed kwant perfectly with python 3.12, but when I tried to install tkwant in the same environment, I got some error shown below, could you please take a look? Thanks in advance. UnsatisfiableError: The following specifications were found to be incompatible with the existing python installation in your environment: Specifications: - tkwant -> python[version='>=3.10,<3.11.0a0|>=3.11,<3.12.0a0|>=3.9,<3.10.0a0|>=3.8,<3.9.0a0|>=3.7,<3.8.0a0|>=3.6,<3.7.0a0'] Your python: python=3.12 If python is on the left-most side of the chain, that's the version you've asked for. When python appears to the right, that indicates that the thing on the left is somehow not available for the python version you are constrained to. Note that conda will not change your python version to a different minor version unless you explicitly specify that. The following specifications were found to be incompatible with your system: - feature:/linux-64::__glibc==2.28=0 - feature:/linux-64::__unix==0=0 - feature:|@/linux-64::__glibc==2.28=0 - feature:|@/linux-64::__unix==0=0 - tkwant -> cython -> __glibc[version='>=2.17|>=2.17,<3.0.a0'] - tkwant -> sympy -> __unix

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KWANT installation failure
by Gavin Nop Oct. 23, 2024

Oct. 23, 2024

Hi, I've tried several methods to mitigate this, but am unable to determine the root cause. pip install kwant fails on a new install of ubuntu. I have an ARM cpu which I believe should be compatible, however, I always get the following error. Thanks for any help! Collecting kwant Using cached kwant-1.5.0.tar.gz (1.7 MB) Preparing metadata (setup.py) ... done Requirement already satisfied: numpy>=1.18.0 in ./miniconda3/lib/python3.12/site-packages (from kwant) (2.1.2) Collecting scipy!=1.6.1,>=1.3.0 (from kwant) Using cached scipy-1.14.1-cp312-cp312-manylinux_2_17_x86_64.manylinux2014_x86_64.whl.metadata (60 kB) Collecting tinyarray>=1.2.2 (from kwant) Using cached tinyarray-1.2.4-cp312-cp312-linux_x86_64.whl Using cached scipy-1.14.1-cp312-cp312-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (40.8 MB) Building wheels for collected packages: kwant Building wheel for kwant (setup.py) ... error *error*: *subprocess-exited-with-error* × python setup.py bdist_wheel did not run successfully. │ exit code: *1* ╰─> [130 lines of output] running bdist_wheel running build running build_py creating build creating build/lib.linux-x86_64-cpython-312 creating build/lib.linux-x86_64-cpython-312/kwant copying kwant/qsymm.py -> build/lib.linux-x86_64-cpython-312/kwant copying kwant/_colormaps.py -> build/lib.linux-x86_64-cpython-312/kwant copying kwant/_plotter.py -> build/lib.linux-x86_64-cpython-312/kwant copying kwant/rmt.py -> build/lib.linux-x86_64-cpython-312/kwant copying kwant/digest.py -> build/lib.linux-x86_64-cpython-312/kwant copying kwant/_common.py -> build/lib.linux-x86_64-cpython-312/kwant copying kwant/wraparound.py -> build/lib.linux-x86_64-cpython-312/kwant copying kwant/version.py -> build/lib.linux-x86_64-cpython-312/kwant copying kwant/kpm.py -> build/lib.linux-x86_64-cpython-312/kwant copying kwant/lattice.py -> build/lib.linux-x86_64-cpython-312/kwant copying kwant/system.py -> build/lib.linux-x86_64-cpython-312/kwant copying kwant/_kwant_version.py -> build/lib.linux-x86_64-cpython-312/kwant copying kwant/plotter.py -> build/lib.linux-x86_64-cpython-312/kwant copying kwant/builder.py -> build/lib.linux-x86_64-cpython-312/kwant copying kwant/__init__.py -> build/lib.linux-x86_64-cpython-312/kwant creating build/lib.linux-x86_64-cpython-312/kwant/linalg copying kwant/linalg/cmumps.py -> build/lib.linux-x86_64-cpython-312/kwant/linalg copying kwant/linalg/fortran_helpers.py -> build/lib.linux-x86_64-cpython-312/kwant/linalg copying kwant/linalg/mumps.py -> build/lib.linux-x86_64-cpython-312/kwant/linalg copying kwant/linalg/decomp_schur.py -> build/lib.linux-x86_64-cpython-312/kwant/linalg copying kwant/linalg/lll.py -> build/lib.linux-x86_64-cpython-312/kwant/linalg copying kwant/linalg/__init__.py -> build/lib.linux-x86_64-cpython-312/kwant/linalg creating build/lib.linux-x86_64-cpython-312/kwant/graph copying kwant/graph/defs.py -> build/lib.linux-x86_64-cpython-312/kwant/graph copying kwant/graph/__init__.py -> build/lib.linux-x86_64-cpython-312/kwant/graph creating build/lib.linux-x86_64-cpython-312/kwant/physics copying kwant/physics/symmetry.py -> build/lib.linux-x86_64-cpython-312/kwant/physics copying kwant/physics/leads.py -> build/lib.linux-x86_64-cpython-312/kwant/physics copying kwant/physics/dispersion.py -> build/lib.linux-x86_64-cpython-312/kwant/physics copying kwant/physics/noise.py -> build/lib.linux-x86_64-cpython-312/kwant/physics copying kwant/physics/gauge.py -> build/lib.linux-x86_64-cpython-312/kwant/physics copying kwant/physics/__init__.py -> build/lib.linux-x86_64-cpython-312/kwant/physics creating build/lib.linux-x86_64-cpython-312/kwant/solvers copying kwant/solvers/common.py -> build/lib.linux-x86_64-cpython-312/kwant/solvers copying kwant/solvers/default.py -> build/lib.linux-x86_64-cpython-312/kwant/solvers copying kwant/solvers/mumps.py -> build/lib.linux-x86_64-cpython-312/kwant/solvers copying kwant/solvers/sparse.py -> build/lib.linux-x86_64-cpython-312/kwant/solvers copying kwant/solvers/__init__.py -> build/lib.linux-x86_64-cpython-312/kwant/solvers creating build/lib.linux-x86_64-cpython-312/kwant/tests copying kwant/tests/test_operator.py -> build/lib.linux-x86_64-cpython-312/kwant/tests copying kwant/tests/test_plotter.py -> build/lib.linux-x86_64-cpython-312/kwant/tests copying kwant/tests/test_system.py -> build/lib.linux-x86_64-cpython-312/kwant/tests copying kwant/tests/test_lattice.py -> build/lib.linux-x86_64-cpython-312/kwant/tests copying kwant/tests/test_wraparound.py -> build/lib.linux-x86_64-cpython-312/kwant/tests copying kwant/tests/test_qsymm.py -> build/lib.linux-x86_64-cpython-312/kwant/tests copying kwant/tests/test_rmt.py -> build/lib.linux-x86_64-cpython-312/kwant/tests copying kwant/tests/test_kpm.py -> build/lib.linux-x86_64-cpython-312/kwant/tests copying kwant/tests/test_comprehensive.py -> build/lib.linux-x86_64-cpython-312/kwant/tests copying kwant/tests/__init__.py -> build/lib.linux-x86_64-cpython-312/kwant/tests copying kwant/tests/test_builder.py -> build/lib.linux-x86_64-cpython-312/kwant/tests creating build/lib.linux-x86_64-cpython-312/kwant/continuum copying kwant/continuum/discretizer.py -> build/lib.linux-x86_64-cpython-312/kwant/continuum copying kwant/continuum/landau_levels.py -> build/lib.linux-x86_64-cpython-312/kwant/continuum copying kwant/continuum/_common.py -> build/lib.linux-x86_64-cpython-312/kwant/continuum copying kwant/continuum/__init__.py -> build/lib.linux-x86_64-cpython-312/kwant/continuum creating build/lib.linux-x86_64-cpython-312/kwant/linalg/tests copying kwant/linalg/tests/test_lll.py -> build/lib.linux-x86_64-cpython-312/kwant/linalg/tests copying kwant/linalg/tests/_test_utils.py -> build/lib.linux-x86_64-cpython-312/kwant/linalg/tests copying kwant/linalg/tests/test_linalg.py -> build/lib.linux-x86_64-cpython-312/kwant/linalg/tests copying kwant/linalg/tests/test_mumps.py -> build/lib.linux-x86_64-cpython-312/kwant/linalg/tests copying kwant/linalg/tests/__init__.py -> build/lib.linux-x86_64-cpython-312/kwant/linalg/tests creating build/lib.linux-x86_64-cpython-312/kwant/graph/tests copying kwant/graph/tests/test_scotch.py -> build/lib.linux-x86_64-cpython-312/kwant/graph/tests copying kwant/graph/tests/test_core.py -> build/lib.linux-x86_64-cpython-312/kwant/graph/tests copying kwant/graph/tests/__init__.py -> build/lib.linux-x86_64-cpython-312/kwant/graph/tests creating build/lib.linux-x86_64-cpython-312/kwant/physics/tests copying kwant/physics/tests/test_leads.py -> build/lib.linux-x86_64-cpython-312/kwant/physics/tests copying kwant/physics/tests/test_gauge.py -> build/lib.linux-x86_64-cpython-312/kwant/physics/tests copying kwant/physics/tests/test_noise.py -> build/lib.linux-x86_64-cpython-312/kwant/physics/tests copying kwant/physics/tests/test_dispersion.py -> build/lib.linux-x86_64-cpython-312/kwant/physics/tests copying kwant/physics/tests/__init__.py -> build/lib.linux-x86_64-cpython-312/kwant/physics/tests copying kwant/physics/tests/test_symmetry.py -> build/lib.linux-x86_64-cpython-312/kwant/physics/tests creating build/lib.linux-x86_64-cpython-312/kwant/solvers/tests copying kwant/solvers/tests/test_solvers.py -> build/lib.linux-x86_64-cpython-312/kwant/solvers/tests copying kwant/solvers/tests/__init__.py -> build/lib.linux-x86_64-cpython-312/kwant/solvers/tests creating build/lib.linux-x86_64-cpython-312/kwant/continuum/tests copying kwant/continuum/tests/test_discretizer.py -> build/lib.linux-x86_64-cpython-312/kwant/continuum/tests copying kwant/continuum/tests/test_common.py -> build/lib.linux-x86_64-cpython-312/kwant/continuum/tests copying kwant/continuum/tests/test_landau_levels.py -> build/lib.linux-x86_64-cpython-312/kwant/continuum/tests copying kwant/continuum/tests/__init__.py -> build/lib.linux-x86_64-cpython-312/kwant/continuum/tests copying kwant/operator.pxd -> build/lib.linux-x86_64-cpython-312/kwant copying kwant/linalg/cmumps.pxd -> build/lib.linux-x86_64-cpython-312/kwant/linalg copying kwant/graph/core.pxd -> build/lib.linux-x86_64-cpython-312/kwant/graph copying kwant/graph/defs.pxd -> build/lib.linux-x86_64-cpython-312/kwant/graph copying kwant/graph/c_scotch.pxd -> build/lib.linux-x86_64-cpython-312/kwant/graph copying kwant/graph/defs.h -> build/lib.linux-x86_64-cpython-312/kwant/graph running build_ext building 'kwant._system' extension creating build/temp.linux-x86_64-cpython-312 creating build/temp.linux-x86_64-cpython-312/kwant gcc -pthread -B /home/gavin-nop/miniconda3/compiler_compat -fno-strict-overflow -DNDEBUG -O2 -Wall -fPIC -O2 -isystem /home/gavin-nop/miniconda3/include -fPIC -O2 -isystem /home/gavin-nop/miniconda3/include -fPIC -DNPY_NO_DEPRECATED_API=NPY_1_7_API_VERSION -Ikwant/graph -I/home/gavin-nop/miniconda3/lib/python3.12/site-packages/numpy/_core/include -I/home/gavin-nop/miniconda3/include/python3.12 -c kwant/_system.c -o build/temp.linux-x86_64-cpython-312/kwant/_system.o In file included from /home/gavin-nop/miniconda3/include/python3.12/Python.h:38, from kwant/_system.c:47: kwant/_system.c: In function ‘__pyx_f_5numpy_PyDataType_SHAPE’: kwant/_system.c:20006:39: error: ‘PyArray_Descr’ {aka ‘struct _PyArray_Descr’} has no member named ‘subarray’ 20006 | __Pyx_INCREF(((PyObject*)__pyx_v_d->subarray->shape)); | ^~ /home/gavin-nop/miniconda3/include/python3.12/pyport.h:24:38: note: in definition of macro ‘_Py_CAST’ 24 | #define _Py_CAST(type, expr) ((type)(expr)) | ^~~~ /home/gavin-nop/miniconda3/include/python3.12/object.h:661:35: note: in expansion of macro ‘_PyObject_CAST’ 661 | # define Py_INCREF(op) Py_INCREF(_PyObject_CAST(op)) | ^~~~~~~~~~~~~~ kwant/_system.c:2356:27: note: in expansion of macro ‘Py_INCREF’ 2356 | #define __Pyx_INCREF(r) Py_INCREF(r) | ^~~~~~~~~ kwant/_system.c:20006:5: note: in expansion of macro ‘__Pyx_INCREF’ 20006 | __Pyx_INCREF(((PyObject*)__pyx_v_d->subarray->shape)); | ^~~~~~~~~~~~ kwant/_system.c:20007:36: error: ‘PyArray_Descr’ {aka ‘struct _PyArray_Descr’} has no member named ‘subarray’ 20007 | __pyx_r = ((PyObject*)__pyx_v_d->subarray->shape); | ^~ ************************************ Error ************************************ The compilation of Kwant has failed. Please examine the error message above and consult the installation instructions in README.rst. You might have to customize build.conf. Build configuration was: ['No MUMPS support'] ******************************************************************************* error: command '/usr/bin/gcc' failed with exit code 1 [end of output] *note*: This error originates from a subprocess, and is likely not a problem with pip. ERROR: Failed building wheel for kwant Running setup.py clean for kwant Failed to build kwantERROR: ERROR: Failed to build installable wheels for some pyproject.toml based projects (kwant)

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To to separate spins, electron and hole
by Khani Hosein Oct. 11, 2024

Oct. 11, 2024

Dear all, I am using Kwant to study a system with both spins and electron and hole, so the hopping matrix is 4X4. Now I want to know how to separate the spins, electron and hole. I study this through the "2.6. Superconductors: orbital degrees of freedom, conservation laws and symmetries" smatrix = kwant.smatrix(syst, energy) data.append(smatrix.submatrix((0, 0), (0, 0)).shape[0] -smatrix.transmission((0, 0), (0, 0)) +smatrix.transmission((0, 1), (0, 0))) I do not find more information about this for kwant. For my system, if I have 3 leads, and the hopping and onsite energy is set in this order: (e↑,0,0,0)- spin up electron,first row of the 4X4matrix (0,e↓,0,0)- spin down electron,second row of the 4X4matrix (0,0, h↑ ,0)- spin up hole,third row of the 4X4matrix (0,0, 0, h ↓ )- spin down hole,fourth row of the 4X4matrix I want to obtain the transmissions from 0 →2. smatrix = kwant.smatrix(syst, energy) The transmission from h↑ to e↑ is: smatrix.transmission((2, 1), (0, 2)) The transmission from h ↓ to e↑ is: smatrix.transmission((2, 1), (0, 3)) Is my understanding correct? Thanks very much in advance! Hosein Khani

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Alternative procedure to calculate the quantum Hall conductivity?
by adiptapal7＠gmail.com Oct. 9, 2024

Oct. 9, 2024

Hello Kwant users, I have been trying to calculate the Hall conductivity in a time reversal broken Weyl semimetal (Weyl axis z) by using a 6-terminal Hall bar geometry with two current leads along z and 4 voltage leads perpendicular to z and then injecting unit current through the left current lead and calculate the p.d. across the voltage leads by inverting the conductance matrix as shown in qhe.py. However, it seems for some cases in thin film systems (thin film along x), the conductance matrix is singular and I cannot get results. Is there an alternative way to calculate the Hall conductivity in this case where one does not need to invert the conductance matrix? Thanks in advance.

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