From 383f84350cd0aa04d7f16c05512f229af279b105 Mon Sep 17 00:00:00 2001
From: Joseph Weston <joseph@weston.cloud>
Date: Wed, 3 Jul 2019 15:21:53 +0200
Subject: [PATCH] set discrete symmetries and conservation law when attaching
lead
Previously when 'attach_lead' would expand a lead unit cell to deal
with greater than nearest-neighbor hoppings it would unset the
conservation law and discrete symmetries of the lead.
Closes #303.
---
kwant/builder.py | 8 +++++++-
kwant/tests/test_builder.py | 13 +++++++++++--
2 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/kwant/builder.py b/kwant/builder.py
index 79e1f019..2ca81a94 100644
--- a/kwant/builder.py
+++ b/kwant/builder.py
@@ -1681,7 +1681,13 @@ class Builder:
if hop_range > 1:
# Automatically increase the period, potentially warn the user.
- new_lead = Builder(sym.subgroup((hop_range,)))
+ new_lead = Builder(
+ sym.subgroup((hop_range,)),
+ conservation_law=lead_builder.conservation_law,
+ time_reversal=lead_builder.time_reversal,
+ particle_hole=lead_builder.particle_hole,
+ chiral=lead_builder.chiral,
+ )
with reraise_warnings():
new_lead.fill(lead_builder, lambda site: True,
lead_builder.sites(), max_sites=float('inf'))
diff --git a/kwant/tests/test_builder.py b/kwant/tests/test_builder.py
index c6f08748..bd02f680 100644
--- a/kwant/tests/test_builder.py
+++ b/kwant/tests/test_builder.py
@@ -843,7 +843,7 @@ def test_fill_sticky():
def test_attach_lead():
- fam = builder.SimpleSiteFamily()
+ fam = builder.SimpleSiteFamily(norbs=1)
fam_noncommensurate = builder.SimpleSiteFamily(name='other')
syst = builder.Builder()
@@ -878,7 +878,12 @@ def test_attach_lead():
# add some further-than-nearest-neighbor hoppings
hop_range = 3
- lead = builder.Builder(VerySimpleSymmetry(1))
+ lead = builder.Builder(
+ VerySimpleSymmetry(1),
+ conservation_law=np.eye(1),
+ time_reversal=np.eye(1),
+ particle_hole=np.eye(1),
+ chiral=np.eye(1))
lead[fam(0)] = 1
for i in range(1, hop_range + 1):
lead[fam(0), fam(i)] = 1
@@ -886,6 +891,10 @@ def test_attach_lead():
expanded_lead = syst.leads[-1].builder
assert expanded_lead.symmetry.period == hop_range
assert len(list(expanded_lead.sites())) == hop_range
+ assert expanded_lead.conservation_law is lead.conservation_law
+ assert expanded_lead.time_reversal is lead.time_reversal
+ assert expanded_lead.particle_hole is lead.particle_hole
+ assert expanded_lead.chiral is lead.chiral
# check that we can actually finalize the system
syst.finalized()
--
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