Commit 4f14e68d authored by Joseph Weston's avatar Joseph Weston

Merge branch 'doc/jupyter-sphinx' into 'master'

Convert tutorial building machinery to Jupyter-Sphinx.

Closes #87

See merge request kwant/kwant!296
parents c7eefacb 53dfb1e8
Pipeline #17857 passed with stages
in 9 minutes and 15 seconds
......@@ -8,13 +8,7 @@
/dist
/doc/build
/doc/source/reference/generated/
/doc/source/code/include/*.py
/doc/source/code/figure/*.png
/doc/source/code/figure/*.pdf
/doc/source/code/figure/.*_flag
/doc/source/code/figure/[a-zA-Z]*.py
/doc/source/code/figure/*.txt
/doc/source/code/download/
/doc/source/figure/*.pdf
/build.conf
/kwant.egg-info/
/MANIFEST.in
......
......@@ -239,7 +239,10 @@ build documentation:
- build:latest
stage: test
script:
- make -C doc realclean; make -C doc html SPHINXOPTS='-A website_deploy=True -n -W' SOURCE_LINK_TEMPLATE="$CI_PROJECT_URL"/blob/\$\$r/\$\$f
- apt-get update && apt-get install -y librsvg2-bin # for converting svgs to pdfs
- pip install git+https://github.com/jupyter-widgets/jupyter-sphinx sphinxcontrib-svg2pdfconverter
- python -m ipykernel install --user --name kwant-latest
- make -C doc clean; make -C doc html SPHINXOPTS='-A website_deploy=True -n -W -D jupyter_execute_default_kernel=kwant-latest' SOURCE_LINK_TEMPLATE="$CI_PROJECT_URL"/blob/\$\$r/\$\$f
artifacts:
paths:
- doc/build/html/
......@@ -251,7 +254,10 @@ build PDF documentation:
- build:latest
stage: test
script:
- make -C doc latex SPHINXOPTS='-n -W'
- apt-get update && apt-get install -y librsvg2-bin # for converting svgs to pdfs
- pip install git+https://github.com/jupyter-widgets/jupyter-sphinx sphinxcontrib-svg2pdfconverter
- python -m ipykernel install --user --name kwant-latest
- make -C doc latex SPHINXOPTS='-n -W -D jupyter_execute_default_kernel=kwant-latest'
- cd doc/build/latex
- make all-pdf
artifacts:
......
......@@ -144,9 +144,11 @@ Building the documentation
To build the documentation, the `Sphinx documentation generator
<http://www.sphinx-doc.org/en/stable/>`_ is required with ``numpydoc`` extension
(version 0.5 or newer). If PDF documentation is to be built, the tools
from the `libRSVG <https://wiki.gnome.org/action/show/Projects/LibRsvg>`_ (Debian/Ubuntu package
``librsvg2-bin``) are needed to convert SVG drawings into the PDF format.
(version 0.5 or newer), as well as ``jupyter-sphinx`` (version 0.2 or newer).
If PDF documentation is to be built, the tools
from the `libRSVG <https://wiki.gnome.org/action/show/Projects/LibRsvg>`_
(Debian/Ubuntu package ``librsvg2-bin``) are needed to convert SVG drawings
into the PDF format.
As a prerequisite for building the documentation, Kwant must have been built
successfully using ``python3 setup.py build`` as described above (or Kwant must
......@@ -160,25 +162,6 @@ Because of some quirks of how Sphinx works, it might be necessary to execute
done, Sphinx may mistakenly use PNG files for PDF output or other problems may
appear.
When ``make html`` is run, modified tutorial example scripts are executed to
update any figures that might have changed. The machinery behind this works as
follows. The canonical source for a tutorial script, say ``graphene.py`` is
the file ``doc/source/images/graphene.py.diff``. This diff file contains the
information to recreate two versions of ``graphene.py``: a version that is
presented in the documentation (``doc/source/tutorial/graphene.py``), and a
version that is used to generate the figures for the documentation
(``doc/source/images/graphene.py``). Both versions are related but differ
e.g. in the details of the plotting. When ``make html`` is run, both versions
are extracted form the diff file.
The diff file may be modified directly. Another possible way of working is to
directly modify either the tutorial script or the figure generation script.
Then ``make html`` will use the command line tool `wiggle
<https://github.com/neilbrown/wiggle>`_ to propagate the modifications accordingly.
This will often just work, but may sometimes result in conflicts, in which case
a message will be printed. The conflicts then have to be resolved much like
with a version control system.
****************************
Hints for specific platforms
****************************
......
# Makefile for Sphinx documentation
# Copyright 2011-2017 Kwant authors.
# Minimal makefile for Sphinx documentation
#
# This file is part of Kwant. It is subject to the license terms in the file
# LICENSE.rst found in the top-level directory of this distribution and at
# http://kwant-project.org/license. A list of Kwant authors can be found in
# the file AUTHORS.rst at the top-level directory of this distribution and at
# http://kwant-project.org/authors.
# You can set these variables from the command line.
SPHINXOPTS =
SPHINXBUILD = python3 -c 'import sys, sphinx; sys.exit(sphinx.main(sys.argv))'
PAPER =
SPHINXBUILD = sphinx-build
SOURCEDIR = source
BUILDDIR = build
# Internal variables.
PAPEROPT_a4 = -D latex_paper_size=a4
PAPEROPT_letter = -D latex_paper_size=letter
ALLSPHINXOPTS = -d $(BUILDDIR)/doctrees $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) source
# Put it first so that "make" without argument is like "make help".
help:
@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
.PHONY: help Makefile
# We convert all SVG files to PDF for LaTeX output. For HTML output, we don't
# create PNGs but rather use the SVG files directly.
FIGURESOURCES = $(shell find source -name "*.svg")
GENERATEDPDF = $(patsubst %.svg,%.pdf,$(FIGURESOURCES))
# Figure generation from patched tutorial scripts
#
# As make does not support the generation of multiple targets by a single
# invocation of a (non-implicit) rule, we use a trick: We pretend to be
# generating a single (empty) flag file per invocation. The figure files are
# generated as well, but only as side-effects. Each flag file is used to
# remember the time at which the corresponding figure-generating script was run.
# This works perfectly unless the actual output files are deleted without
# deleting the corresponding flag file.
FIGSCRIPTS = $(patsubst %.diff,%,$(notdir $(wildcard source/code/figure/*.py.diff)))
FIGURES = $(patsubst %.py,source/code/figure/.%_flag,$(FIGSCRIPTS))
SCRIPTS = $(sort $(FIGSCRIPTS) $(notdir $(wildcard source/code/include/*.py)))
INCLUDES = $(patsubst %,source/code/include/%,$(SCRIPTS))
DOWNLOADS = $(patsubst %,source/code/download/%,$(SCRIPTS))
.PHONY: help clean realclean html dirhtml pickle json htmlhelp qthelp latex changes linkcheck doctest
help:
@echo "Please use \`make <target>' where <target> is one of"
@echo " html to make standalone HTML files"
@echo " dirhtml to make HTML files named index.html in directories"
@echo " pickle to make pickle files"
@echo " json to make JSON files"
@echo " htmlhelp to make HTML files and a HTML help project"
@echo " qthelp to make HTML files and a qthelp project"
@echo " latex to make LaTeX files, you can set PAPER=a4 or PAPER=letter"
@echo " changes to make an overview of all changed/added/deprecated items"
@echo " linkcheck to check all external links for integrity"
@echo " doctest to run all doctests embedded in the documentation (if enabled)"
@echo
@echo "Append SPHINXOPTS='-A website_deploy=True' to include web analytics code."
clean:
-rm -rf $(BUILDDIR)/* $(GENERATEDPDF)
-rm -rf source/reference/generated
realclean: clean
-rm -f $(FIGURES)
-rm -f $(patsubst %,source/code/include/%,$(FIGSCRIPTS))
-rm -f $(DOWNLOADS)
-rm -f $(patsubst %,source/code/figure/%,$(FIGSCRIPTS))
-rm -f $(patsubst %.py,source/code/figure/%_*.png,$(FIGSCRIPTS))
-rm -f $(patsubst %.py,source/code/figure/%_*.pdf,$(FIGSCRIPTS))
html: $(FIGURES) $(INCLUDES) $(DOWNLOADS)
$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html
@echo
@echo "Build finished. The HTML pages are in $(BUILDDIR)/html."
dirhtml: $(FIGURES) $(INCLUDES) $(DOWNLOADS)
$(SPHINXBUILD) -b dirhtml $(ALLSPHINXOPTS) $(BUILDDIR)/dirhtml
@echo
@echo "Build finished. The HTML pages are in $(BUILDDIR)/dirhtml."
pickle: $(FIGURES) $(INCLUDES) $(DOWNLOADS)
$(SPHINXBUILD) -b pickle $(ALLSPHINXOPTS) $(BUILDDIR)/pickle
@echo
@echo "Build finished; now you can process the pickle files."
json: $(FIGURES) $(INCLUDES) $(DOWNLOADS)
$(SPHINXBUILD) -b json $(ALLSPHINXOPTS) $(BUILDDIR)/json
@echo
@echo "Build finished; now you can process the JSON files."
htmlhelp: $(FIGURES) $(INCLUDES) $(DOWNLOADS)
$(SPHINXBUILD) -b htmlhelp $(ALLSPHINXOPTS) $(BUILDDIR)/htmlhelp
@echo
@echo "Build finished; now you can run HTML Help Workshop with the" \
".hhp project file in $(BUILDDIR)/htmlhelp."
qthelp: $(FIGURES) $(INCLUDES) $(DOWNLOADS)
$(SPHINXBUILD) -b qthelp $(ALLSPHINXOPTS) $(BUILDDIR)/qthelp
@echo
@echo "Build finished; now you can run "qcollectiongenerator" with the" \
".qhcp project file in $(BUILDDIR)/qthelp, like this:"
@echo "# qcollectiongenerator $(BUILDDIR)/qthelp/kwant.qhcp"
@echo "To view the help file:"
@echo "# assistant -collectionFile $(BUILDDIR)/qthelp/kwant.qhc"
latex: $(GENERATEDPDF) $(FIGURES) $(INCLUDES) $(DOWNLOADS)
$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
@echo
@echo "Build finished; the LaTeX files are in $(BUILDDIR)/latex."
@echo "Run \`make all-pdf' or \`make all-ps' in that directory to" \
"run these through (pdf)latex."
changes:
$(SPHINXBUILD) -b changes $(ALLSPHINXOPTS) $(BUILDDIR)/changes
@echo
@echo "The overview file is in $(BUILDDIR)/changes."
linkcheck:
$(SPHINXBUILD) -b linkcheck $(ALLSPHINXOPTS) $(BUILDDIR)/linkcheck
@echo
@echo "Link check complete; look for any errors in the above output " \
"or in $(BUILDDIR)/linkcheck/output.txt."
doctest:
$(SPHINXBUILD) -b doctest $(ALLSPHINXOPTS) $(BUILDDIR)/doctest
@echo "Testing of doctests in the sources finished, look at the " \
"results in $(BUILDDIR)/doctest/output.txt."
%.pdf: %.svg
inkscape --export-pdf=$@ $<
#### Tutorial and figure script generation machinery ####
# See source/code/README for an explanation.
# Make tutorial scripts by extracting the (complete!) context of the "patches".
# We make sure not to use 'wiggle' here.
.SECONDARY:
source/code/include/%.py: source/code/figure/%.py.diff
@sed -n '/^[- ]/ s/^.//p' <$< >$@
@touch -r $< $@
# Emtpy target required so that the default target is not triggered
%.svg:
source/code/download/%.py: source/code/include/%.py
@mkdir -p source/code/download
@grep -v '^#HIDDEN' <$< >$@
# Make the figure generation scripts by patching tutorial scripts. If the
# tutorial scripts haven't been modified, don't patch but directly extract the
# figure generation scripts. This means that 'wiggle' is only needed when the
# tutorial scripts have been modified.
.SECONDARY:
source/code/figure/%.py: source/code/include/%.py
@if [ $< -nt $@.diff ]; then \
cp $< $@; \
rm -f $@.porig; \
if ! wiggle --replace $@ $@.diff; then \
command -v wiggle >/dev/null 2>&1 && \
echo "Resolve conflicts by editing the files named below"; \
touch -d@0 $@; \
exit 1; \
fi \
else \
sed -n '/^[+ ]/ s/^.//p' <$@.diff >$@; \
touch -r $@.diff $@; \
fi
# Make the figure generation scripts also depend on the diffs.
define makedep
source/code/figure/$(1): source/code/figure/$(1).diff
endef
$(foreach name,$(FIGSCRIPTS),$(eval $(call makedep,$(name))))
# Run an figure generation script. When successful, and if the script is newer
# than the corresponding diff, recreate the latter. Note that the
# corresponding tutorial script cannot be newer, since if it is, the figure
# generation script is generated from it by patching.
source/code/figure/.%_flag: source/code/figure/%.py
cd $(dir $<) && python3 $(notdir $<)
@if [ ! -f $<.diff -o $< -nt $<.diff ]; then \
wiggle --diff --lines source/code/include/$(notdir $<) $< >$<.diff; \
touch -r $< $<.diff; \
fi
@rm -f $<.porig
@touch $@
clean:
rm -f $(GENERATEDPDF)
@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
latex: Makefile $(GENERATEDPDF)
cd .. ; python setup.py build ; cd -
@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
# Catch-all target: route all unknown targets to Sphinx using the new
# "make mode" option. $(O) is meant as a shortcut for $(SPHINXOPTS).
%: Makefile
cd .. ; python setup.py build ; cd -
@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
This directory contains the code examples from the documentation.
Most scripts are present in three related but different versions that
correspond to three different usages.
* Subdirectory 'figure': scripts used for figure generation. Figures
are not displayed but saved to disk.
* Subdirectory 'include': scripts that display figures on screen.
They contain commented marks for including snippets in the
documentation.
* Subdirectory 'download': complete scripts to be offered for download
by readers. Like 'include' but with the include marks removed.
Most scripts are extracted from corresponding '*.py.diff' files inside
'figure/'. These are patches from the 'include' version to the
'figure' version. The patches include complete context and as such
can be used to recreate both files. It's these patches that are kept
under version control.
running 'make html' or 'make latex' inside '/doc' will automatically
update all these scripts according to the following scheme:
---->------------->------
/ \
/ download/x.py \
figure/x.py.diff ^ \
^ \ | \
| -> include/x.py ---(patch)---> figure/x.py
| | |
| | |
\ v /
----<----------(diff)--------------<--------
Thus, it is possible to update figure/x.py.diff, include/x.py or
figure/x.py and any changes will be propagated automatically when
'make' is run. (Only download/x.py is a dead end.) The user will be
informed about any conflicts. The makefile will only update files
that are older than their sources and is careful to propagate time
stamps in order to avoid infinite loops.
Editing only figure/x.py.diff is a sure way to avoid any conflicts.
################################################################
# Make matplotlib work without X11
################################################################
import matplotlib
matplotlib.use('Agg')
################################################################
# Prepend Kwant's build directory to sys.path
################################################################
import sys
from distutils.util import get_platform
sys.path.insert(0, "../../../../build/lib.{0}-{1}.{2}".format(
get_platform(), *sys.version_info[:2]))
################################################################
# Define constants for plotting
################################################################
pt_to_in = 1. / 72.
# Default width of figures in pts
figwidth_pt = 600
figwidth_in = figwidth_pt * pt_to_in
# Width for smaller figures
figwidth_small_pt = 400
figwidth_small_in = figwidth_small_pt * pt_to_in
# Sizes for matplotlib figures
mpl_width_in = figwidth_pt * pt_to_in
mpl_label_size = None # font sizes in points
mpl_tick_size = None
# dpi for conversion from inches
dpi = 90
@@ -1,127 +1,196 @@
# Tutorial 2.3.3. Nontrivial shapes
# =================================
#
# Physics background
# ------------------
# Flux-dependent transmission through a quantum ring
#
# Kwant features highlighted
# --------------------------
# - More complex shapes with lattices
# - Allows for discussion of subtleties of `attach_lead` (not in the
# example, but in the tutorial main text)
# - Modifcations of hoppings/sites after they have been added
+import _defs
from cmath import exp
from math import pi
import kwant
# For plotting
from matplotlib import pyplot
#HIDDEN_BEGIN_eusz
def make_system(a=1, t=1.0, W=10, r1=10, r2=20):
# Start with an empty tight-binding system and a single square lattice.
# `a` is the lattice constant (by default set to 1 for simplicity).
lat = kwant.lattice.square(a)
syst = kwant.Builder()
#### Define the scattering region. ####
# Now, we aim for a more complex shape, namely a ring (or annulus)
def ring(pos):
(x, y) = pos
rsq = x ** 2 + y ** 2
return (r1 ** 2 < rsq < r2 ** 2)
#HIDDEN_END_eusz
# and add the corresponding lattice points using the `shape`-function
#HIDDEN_BEGIN_lcak
syst[lat.shape(ring, (0, r1 + 1))] = 4 * t
syst[lat.neighbors()] = -t
#HIDDEN_END_lcak
# In order to introduce a flux through the ring, we introduce a phase on
# the hoppings on the line cut through one of the arms. Since we want to
# change the flux without modifying the Builder instance repeatedly, we
# define the modified hoppings as a function that takes the flux as its
# parameter phi.
#HIDDEN_BEGIN_lvkt
def hopping_phase(site1, site2, phi):
return -t * exp(1j * phi)
def crosses_branchcut(hop):
ix0, iy0 = hop[0].tag
# builder.HoppingKind with the argument (1, 0) below
# returns hoppings ordered as ((i+1, j), (i, j))
return iy0 < 0 and ix0 == 1 # ix1 == 0 then implied
# Modify only those hopings in x-direction that cross the branch cut
def hops_across_cut(syst):
for hop in kwant.builder.HoppingKind((1, 0), lat, lat)(syst):
if crosses_branchcut(hop):
yield hop
syst[hops_across_cut] = hopping_phase
#HIDDEN_END_lvkt
#### Define the leads. ####
# left lead
#HIDDEN_BEGIN_qwgr
sym_lead = kwant.TranslationalSymmetry((-a, 0))
lead = kwant.Builder(sym_lead)
def lead_shape(pos):
(x, y) = pos
return (-W / 2 < y < W / 2)
lead[lat.shape(lead_shape, (0, 0))] = 4 * t
lead[lat.neighbors()] = -t
#HIDDEN_END_qwgr
#### Attach the leads and return the system. ####
#HIDDEN_BEGIN_skbz
syst.attach_lead(lead)
syst.attach_lead(lead.reversed())
#HIDDEN_END_skbz
return syst
+def make_system_note1(a=1, t=1.0, W=10, r1=10, r2=20):
+ lat = kwant.lattice.square(a)
+ syst = kwant.Builder()
+ def ring(pos):
+ (x, y) = pos
+ rsq = x**2 + y**2
+ return ( r1**2 < rsq < r2**2)
+ syst[lat.shape(ring, (0, 11))] = 4 * t
+ syst[lat.neighbors()] = -t
+ sym_lead0 = kwant.TranslationalSymmetry((-a, 0))
+ lead0 = kwant.Builder(sym_lead0)
+ def lead_shape(pos):
+ (x, y) = pos
+ return (-1 < x < 1) and ( 0.5 * W < y < 1.5 * W )
+ lead0[lat.shape(lead_shape, (0, W))] = 4 * t
+ lead0[lat.neighbors()] = -t
+ lead1 = lead0.reversed()
+ syst.attach_lead(lead0)
+ syst.attach_lead(lead1)
+ return syst
+
+
+def make_system_note2(a=1, t=1.0, W=10, r1=10, r2=20):
+ lat = kwant.lattice.square(a)
+ syst = kwant.Builder()
+ def ring(pos):
+ (x, y) = pos
+ rsq = x**2 + y**2
+ return ( r1**2 < rsq < r2**2)
+ syst[lat.shape(ring, (0, 11))] = 4 * t
+ syst[lat.neighbors()] = -t
+ sym_lead0 = kwant.TranslationalSymmetry((-a, 0))
+ lead0 = kwant.Builder(sym_lead0)
+ def lead_shape(pos):
+ (x, y) = pos
+ return (-1 < x < 1) and ( -W/2 < y < W/2 )
+ lead0[lat.shape(lead_shape, (0, 0))] = 4 * t
+ lead0[lat.neighbors()] = -t
+ lead1 = lead0.reversed()
+ syst.attach_lead(lead0)
+ syst.attach_lead(lead1, lat(0, 0))
+ return syst
+
+
def plot_conductance(syst, energy, fluxes):
# compute conductance
normalized_fluxes = [flux / (2 * pi) for flux in fluxes]
data = []
for flux in fluxes:
smatrix = kwant.smatrix(syst, energy, params=dict(phi=flux))
data.append(smatrix.transmission(1, 0))
- pyplot.figure()
+ fig = pyplot.figure()
pyplot.plot(normalized_fluxes, data)
- pyplot.xlabel("flux [flux quantum]")
- pyplot.ylabel("conductance [e^2/h]")
- pyplot.show()
+ pyplot.xlabel("flux [flux quantum]",
+ fontsize=_defs.mpl_label_size)
+ pyplot.ylabel("conductance [e^2/h]",
+ fontsize=_defs.mpl_label_size)
+ pyplot.setp(fig.get_axes()[0].get_xticklabels(),
+ fontsize=_defs.mpl_tick_size)
+ pyplot.setp(fig.get_axes()[0].get_yticklabels(),
+ fontsize=_defs.mpl_tick_size)
+ fig.set_size_inches(_defs.mpl_width_in, _defs.mpl_width_in * 3. / 4.)
+ fig.subplots_adjust(left=0.15, right=0.95, top=0.95, bottom=0.15)
+ fig.savefig("ab_ring_result.pdf")
+ fig.savefig("ab_ring_result.png", dpi=_defs.dpi)
def main():
syst = make_system()
# Check that the system looks as intended.
- kwant.plot(syst)
+ size = (_defs.figwidth_in, _defs.figwidth_in)
+ for extension in ('pdf', 'png'):
+ kwant.plot(syst, file="ab_ring_syst." + extension,
+ fig_size=size, dpi=_defs.dpi)
+
# Finalize the system.
syst = syst.finalized()
# We should see a conductance that is periodic with the flux quantum
plot_conductance(syst, energy=0.15, fluxes=[0.01 * i * 3 * 2 * pi
for i in range(100)])
+ # Finally, some plots needed for the notes
+ syst = make_system_note1()
+ for extension in ('pdf', 'png'):
+ kwant.plot(syst, file="ab_ring_note1." + extension,
+ fig_size=size, dpi=_defs.dpi)
+ syst = make_system_note2()
+ for extension in ('pdf', 'png'):
+ kwant.plot(syst, file="ab_ring_note2." + extension,
+ fig_size=size, dpi=_defs.dpi)
+
+
# Call the main function if the script gets executed (as opposed to imported).
# See <http://docs.python.org/library/__main__.html>.
if __name__ == '__main__':
main()
@@ -1,52 +1,62 @@
# Tutorial 2.4.1. Band structure calculations
# ===========================================
#
# Physics background
# ------------------
# band structure of a simple quantum wire in tight-binding approximation
#
# Kwant features highlighted
# --------------------------
# - Computing the band structure of a finalized lead.
+import _defs
import kwant
# For plotting.
from matplotlib import pyplot
#HIDDEN_BEGIN_zxip
def make_lead(a=1, t=1.0, W=10):
# Start with an empty lead with a single square lattice
lat = kwant.lattice.square(a)
sym_lead = kwant.TranslationalSymmetry((-a, 0))
lead = kwant.Builder(sym_lead)
# build up one unit cell of the lead, and add the hoppings
# to the next unit cell
for j in range(W):
lead[lat(0, j)] = 4 * t
if j > 0:
lead[lat(0, j), lat(0, j - 1)] = -t
lead[lat(1, j), lat(0, j)] = -t
return lead
#HIDDEN_END_zxip
#HIDDEN_BEGIN_pejz
def main():
lead = make_lead().finalized()
- kwant.plotter.bands(lead, show=False)
- pyplot.xlabel("momentum [(lattice constant)^-1]")
- pyplot.ylabel("energy [t]")
- pyplot.show()
+ fig = kwant.plotter.bands(lead, show=False)
+ pyplot.xlabel("momentum [(lattice constant)^-1]",
+ fontsize=_defs.mpl_label_size)
+ pyplot.ylabel("energy [t]", fontsize=_defs.mpl_label_size)
+ pyplot.setp(fig.get_axes()[0].get_xticklabels(),
+ fontsize=_defs.mpl_tick_size)
+ pyplot.setp(fig.get_axes()[0].get_yticklabels(),
+ fontsize=_defs.mpl_tick_size)
+ fig.set_size_inches(_defs.mpl_width_in, _defs.mpl_width_in * 3. / 4.)
+ fig.subplots_adjust(left=0.15, right=0.95, top=0.95, bottom=0.15)
+ for extension in ('pdf', 'png'):
+ fig.savefig("band_structure_result." + extension, dpi=_defs.dpi)
+
#HIDDEN_END_pejz
# Call the main function if the script gets executed (as opposed to imported).
# See <http://docs.python.org/library/__main__.html>.
if __name__ == '__main__':
main()
@@ -1,144 +1,161 @@
# Tutorial 2.4.2. Closed systems
# ==============================
#
# Physics background
# ------------------
# Fock-darwin spectrum of a quantum dot (energy spectrum in
# as a function of a magnetic field)
#
# Kwant features highlighted
# --------------------------
# - Use of `hamiltonian_submatrix` in order to obtain a Hamiltonian
# matrix.
+import _defs
from cmath import exp
import numpy as np
import kwant
# For eigenvalue computation
#HIDDEN_BEGIN_tibv
import scipy.sparse.linalg as sla
#HIDDEN_END_tibv
# For plotting
from matplotlib import pyplot
def make_system(a=1, t=1.0, r=10):
# Start with an empty tight-binding system and a single square lattice.
# `a` is the lattice constant (by default set to 1 for simplicity).
#HIDDEN_BEGIN_qlyd
lat = kwant.lattice.square(a, norbs=1)
syst = kwant.Builder()
# Define the quantum dot
def circle(pos):
(x, y) = pos
rsq = x ** 2 + y ** 2
return rsq < r ** 2
def hopx(site1, site2, B):
# The magnetic field is controlled by the parameter B
y = site1.pos[1]
return -t * exp(-1j * B * y)
syst[lat.shape(circle, (0, 0))] = 4 * t
# hoppings in x-direction
syst[kwant.builder.HoppingKind((1, 0), lat, lat)] = hopx
# hoppings in y-directions
syst[kwant.builder.HoppingKind((0, 1), lat, lat)] = -t
# It's a closed system for a change, so no leads