From 3b60e530199ddd456298dd6025b2cd4824b7f03f Mon Sep 17 00:00:00 2001
From: Dennis Heffels <d.heffels@fz-juelich.de>
Date: Wed, 20 Jan 2021 10:21:27 +0000
Subject: [PATCH] phi_matrix
---
kwant/builder.py | 28 +++++++++++++++++++++-------
kwant/physics/gauge.py | 23 ++++++++++-------------
2 files changed, 31 insertions(+), 20 deletions(-)
diff --git a/kwant/builder.py b/kwant/builder.py
index e01980bd..f65a8e08 100644
--- a/kwant/builder.py
+++ b/kwant/builder.py
@@ -1528,13 +1528,24 @@ class Builder:
_require_system
-def _add_peierls_phase(syst, q, peierls_parameter):
+def _add_peierls_phase(syst, peierls_parameter, signs):
+ def phi_matrix(phi, signs):
+ phase_factors = []
+ for sign in signs:
+ if sign == -1:
+ phase_factors.append(phi.conjugate())
+ elif sign == 1:
+ phase_factors.append(phi)
+ return np.diag(phase_factors)
@memoize
def wrap_hopping(hop):
def f(*args):
a, b, *args, phi = args
- return hop(a, b, *args) * phi(a, b)
+ if signs is not None:
+ return np.dot(hop(a, b, *args), phi_matrix(phi(a, b), signs))
+ else:
+ return hop(a, b, *args) * phi(a, b)
params = ('_site0', '_site1')
if callable(hop):
@@ -1550,7 +1561,10 @@ def _add_peierls_phase(syst, q, peierls_parameter):
const_hoppings = {}
def const_hopping(a, b, phi):
- return const_hoppings[a, b] * phi(a, b)
+ if signs is not None:
+ return np.dot(hop(a, b, *args), phi_matrix(phi(a, b), signs))
+ else:
+ return hop(a, b, *args) * phi(a, b)
# fix the signature
params = ('_site0', '_site1', peierls_parameter)
@@ -1570,8 +1584,8 @@ def _add_peierls_phase(syst, q, peierls_parameter):
BuilderLead(
_add_peierls_phase(
lead.builder,
- q,
peierls_parameter + '_lead{}'.format(i),
+ signs
),
lead.interface,
lead.padding,
@@ -1591,7 +1605,7 @@ def _add_peierls_phase(syst, q, peierls_parameter):
return ret
-def add_peierls_phase(syst, q=1, peierls_parameter='phi', fix_gauge=True):
+def add_peierls_phase(syst, peierls_parameter='phi', fix_gauge=True, signs=None):
"""Add a Peierls phase parameter to a Builder.
Parameters
@@ -1691,10 +1705,10 @@ def add_peierls_phase(syst, q=1, peierls_parameter='phi', fix_gauge=True):
raise TypeError("'add_peierls_phase' does not work with "
"vectorized Builders")
- ret = _add_peierls_phase(syst, q, peierls_parameter).finalized()
+ ret = _add_peierls_phase(syst, peierls_parameter, signs).finalized()
if fix_gauge:
- return ret, wrap_gauge(magnetic_gauge(ret, q))
+ return ret, wrap_gauge(magnetic_gauge(ret))
else:
return ret
diff --git a/kwant/physics/gauge.py b/kwant/physics/gauge.py
index 1ffee248..286b75f3 100644
--- a/kwant/physics/gauge.py
+++ b/kwant/physics/gauge.py
@@ -760,7 +760,7 @@ def _check_composite_system(syst):
### Phase calculation
-def _calculate_phases(loops, pos, previous_phase, flux, q):
+def _calculate_phases(loops, pos, previous_phase, flux):
"""Calculate the phase across the terminal links of a set of loops
Parameters
@@ -788,7 +788,7 @@ def _calculate_phases(loops, pos, previous_phase, flux, q):
for loop in loops:
tail, head = loop[-1], loop[0]
integral = flux([pos(p) for p in loop])
- phase = np.exp(q* 1j * np.pi * integral)
+ phase = np.exp(1j * np.pi * integral)
phases[tail, head] = phase / previous_phase(phases, loop)
return phases
@@ -879,7 +879,7 @@ def _infinite_wrapper(syst, phases, a, b):
return 1
-def _peierls_finite(syst, loops, q, syst_field, tol, average):
+def _peierls_finite(syst, loops, syst_field, tol, average):
integrate = partial(_surface_integral, syst_field,
tol=tol, average=average)
phases = _calculate_phases(
@@ -887,12 +887,11 @@ def _peierls_finite(syst, loops, q, syst_field, tol, average):
syst.pos,
_previous_phase_finite,
integrate,
- q,
)
return partial(_finite_wrapper, syst, phases)
-def _peierls_infinite(syst, loops, q, extended_sites, syst_field, tol, average):
+def _peierls_infinite(syst, loops, extended_sites, syst_field, tol, average):
integrate = partial(_surface_integral, syst_field,
tol=tol, average=average)
phases = _calculate_phases(
@@ -900,12 +899,11 @@ def _peierls_infinite(syst, loops, q, extended_sites, syst_field, tol, average):
lambda i: extended_sites(i).pos,
partial(_previous_phase_infinite, syst.cell_size),
integrate,
- q,
)
return partial(_infinite_wrapper, syst, phases)
-def _peierls_composite(syst, loops, q, which_patch, extended_sites, lead_gauges,
+def _peierls_composite(syst, loops, which_patch, extended_sites, lead_gauges,
syst_field, *lead_fields, tol, average):
if len(lead_fields) != len(syst.leads):
raise ValueError('Magnetic fields must be provided for all leads.')
@@ -925,8 +923,7 @@ def _peierls_composite(syst, loops, q, which_patch, extended_sites, lead_gauges,
lambda i: extended_sites(i).pos,
partial(_previous_phase_composite,
which_patch, extended_sites, lead_phases),
- flux,
- q,
+ flux
)
return (partial(_finite_wrapper, syst, phases), *lead_phases)
@@ -977,21 +974,21 @@ class magnetic_gauge:
>>> kwant.hamiltonian_submatrix(syst, params=params)
"""
- def __init__(self, syst, q=1):
+ def __init__(self, syst):
if isinstance(syst, builder.FiniteSystem):
if syst.leads:
loops, which_patch, extended_sites = _loops_in_composite(syst)
lead_gauges = [magnetic_gauge(lead) for lead in syst.leads]
self._peierls = partial(_peierls_composite, syst,
- loops, q, which_patch,
+ loops, which_patch,
extended_sites, lead_gauges)
else:
loops = _loops_in_finite(syst)
- self._peierls = partial(_peierls_finite, syst, loops, q)
+ self._peierls = partial(_peierls_finite, syst, loops)
elif isinstance(syst, builder.InfiniteSystem):
loops, extended_sites = _loops_in_infinite(syst)
self._peierls = partial(_peierls_infinite, syst,
- loops, q, extended_sites)
+ loops, extended_sites)
else:
raise TypeError('Expected a finalized Builder')
--
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