Fix bugs handling time-reversal symmetry (#25)

There are two problems, first the reduced mapping must be generated without time reversal symmetry, otherwise the k = K + G_0 does not hold. Second, the C_k(G) = C_{-k}(-G) must to used to get the correct spectral density when summing up coefficients.
SMTG-Bham · Jun 28, 2023 · e73b206 · e73b206
1 parent e0c113b
commit e73b206
Show file tree

Hide file tree

Showing 8 changed files with 121 additions and 98 deletions.
diff --git a/easyunfold/__init__.py b/easyunfold/__init__.py
@@ -2,4 +2,4 @@
 Collection of code for band unfolding
 """
 
-__version__ = '0.1.4'
+__version__ = '0.1.5'
diff --git a/easyunfold/cli.py b/easyunfold/cli.py
@@ -169,10 +169,11 @@ def unfold(ctx, data_file, mpl_style_file):
 @click.pass_context
 def unfold_status(ctx):
     """Print the status"""
-    from easyunfold.unfold import UnfoldKSet
+    from easyunfold.unfold import UnfoldKSet, reduce_kpoints
+
     unfoldset: UnfoldKSet = ctx.obj['obj']
     print_symmetry_data(unfoldset)
-    nkpts_sc = len(unfoldset.expansion_results['reduced_sckpts'])
+    nkpts_sc = len(reduce_kpoints(unfoldset.expansion_results['reduced_sckpts'], time_reversal=unfoldset.time_reversal)[0])
     click.echo()
     click.echo(f'No. of k points in the primitive cell           : {unfoldset.nkpts_orig}')
     click.echo(f'No. of supercell k points                       : {nkpts_sc}')

diff --git a/easyunfold/unfold.py b/easyunfold/unfold.py
@@ -7,6 +7,7 @@
 ############################################################
 import re
 from typing import Union, List, Tuple
+from packaging import version
 
 import numpy as np
 import matplotlib.pyplot as plt
@@ -162,8 +163,10 @@ def __init__(self,
         self.dft_code = dft_code
         if metadata is None:
             metadata = {}
+        # Not loaded from a file so populate this field
+        if 'program_version' not in metadata:
+            metadata['program_version'] = __version__
         self.metadata = metadata
-        self.metadata['program_version'] = __version__
         self.transient_quantities = {}
 
         # Transient properties
@@ -172,6 +175,19 @@ def __init__(self,
         if self.expansion_results is None:
             self.expand_pc_kpoints()
 
+        self.check_version()
+
+    def check_version(self):
+        """Check the version of the program"""
+        vnow = version.parse(__version__)
+        vcreated = version.parse(self.metadata['program_version'])
+        if vnow > vcreated:
+            print(f'The data file was generated with easyunfold {vcreated}, current {vnow}.')
+        if vcreated == version.parse('0.1.4'):
+            if self.time_reversal:
+                print(('Version 0.1.4 is known to have a bug with supercell kpoints with time-reversal symmetry\n'
+                       'Please regenerate the data file with a newer version.'))
+
     @property
     def is_calculated(self) -> bool:
         """Show the status of the work"""
@@ -290,7 +306,8 @@ def generate_sc_kpoints(self) -> None:
         # We now have bunch of supercell kpoints for each set of expanded kpoints
         # Try to find duplicated SC kpoints
         all_sc = np.array(all_sc)
-        reduced_sckpts, _, sc_kpts_map = reduce_kpoints(all_sc, time_reversal=self.time_reversal)
+        # Do not use time-reversal symmetry for reduction here, as we need to keep k = K - G_0 valid!
+        reduced_sckpts, _, sc_kpts_map = reduce_kpoints(all_sc, time_reversal=False)
         sc_kpts_map = list(sc_kpts_map)
 
         # Mapping between the pckpts to the reduced sckpts
@@ -321,6 +338,9 @@ def write_sc_kpoints(self,
         if self.expansion_results.get('reduced_sckpts') is None:
             self.generate_sc_kpoints()
         kpoints = np.asarray(self.expansion_results['reduced_sckpts'])
+        # Reduce the number of supercell kpoint via time-reversal symmetry
+        if self.time_reversal:
+            kpoints = reduce_kpoints(kpoints, time_reversal=self.time_reversal)[0]
         weights = None
         if nk_per_split is None:
             if scf_kpoints_and_weights:
@@ -822,19 +842,13 @@ def find_K_index(self, K0: np.ndarray) -> int:
         K0_wrapped = wrap_kpoints(K0)
         for ii in range(self.wfc.nkpts):
             if np.alltrue(np.abs(kpts_wrapped[ii] - K0_wrapped) < 1E-5):
-                return ii + 1
+                return ii + 1, False
             # Check for kpoint related with time-reversal symmetry
             if self.time_reversal and np.alltrue(np.abs(kpts_wrapped[ii] + K0_wrapped) < 1E-5):
-                return ii + 1
+                # This actually returns the index of -K0
+                return ii + 1, True
         raise ValueError('Cannot find the corresponding K-points in WAVECAR!')
 
-    def k2K_map(self, kpath) -> List[int]:
-        """
-        Return the map from primitive-cell k-points to supercell k-points.
-        """
-
-        return [self.find_K_index(find_K_from_k(k, self.M)[0]) - 1 for k in kpath]
-
     def spectral_weight_k(self, k0, whichspin=1):
         r"""
         Spectral weight for a given $k$:
@@ -857,10 +871,18 @@ def spectral_weight_k(self, k0, whichspin=1):
         # k0 = G0 + K0
         K0, G0 = find_K_from_k(k0, self.M)
         # find index of K0
-        ikpt = self.find_K_index(K0)
+        ikpt, time_reversal = self.find_K_index(K0)
 
         # get the overlap G-vectors
         Gvalid, Gall = self.get_ovlap_G(ikpt=ikpt)
+
+        # If this kpoint is actuall -K0, use the relationship C_{k}(G) = C_{-k}*(-G)
+        # Since the coefficients are on a grid, we can just inverse the G vectors (unit of reciprocal lattice vector).
+        # There is no need to take conjugate as we only care about the norm.
+        if time_reversal:
+            Gvalid = -Gvalid
+            Gall = -Gall
+
         # Gnew = Gvalid + k0 - K0
         Goffset = Gvalid + G0[np.newaxis, :]
 

diff --git a/tests/test_data/Si-project/Si_super_deformed/KPOINTS_easyunfold b/tests/test_data/Si-project/Si_super_deformed/KPOINTS_easyunfold
@@ -1,28 +1,28 @@
 supercell kpoints
 25
 Rec
-    0.00000000   0.00000000   0.00000000  1.0
-   -0.50000000   0.25000000   0.25000000  1.0
-    0.00000000   0.25000000   0.00000000  1.0
+   -0.50000000  -0.50000000   0.25000000  1.0
+   -0.50000000  -0.12500000   0.37500000  1.0
    -0.50000000   0.00000000   0.00000000  1.0
-    0.00000000  -0.50000000  -0.50000000  1.0
-    0.00000000  -0.50000000   0.00000000  1.0
-    0.00000000   0.37500000  -0.37500000  1.0
+   -0.50000000   0.25000000   0.25000000  1.0
+   -0.33333333   0.00000000   0.33333333  1.0
    -0.25000000  -0.50000000   0.12500000  1.0
-   -0.50000000  -0.12500000   0.37500000  1.0
+   -0.25000000  -0.50000000   0.37500000  1.0
+   -0.25000000  -0.37500000  -0.50000000  1.0
    -0.25000000  -0.25000000  -0.12500000  1.0
+    0.00000000  -0.50000000  -0.50000000  1.0
+    0.00000000  -0.50000000   0.00000000  1.0
+    0.00000000   0.00000000  -0.50000000  1.0
+    0.00000000   0.00000000   0.00000000  1.0
+    0.00000000   0.12500000  -0.37500000  1.0
     0.00000000   0.12500000  -0.12500000  1.0
+    0.00000000   0.16666667   0.16666667  1.0
+    0.00000000   0.25000000  -0.25000000  1.0
+    0.00000000   0.25000000   0.00000000  1.0
+    0.00000000   0.33333333   0.33333333  1.0
+    0.00000000   0.37500000  -0.37500000  1.0
     0.25000000  -0.50000000   0.37500000  1.0
-    0.25000000   0.25000000  -0.37500000  1.0
-   -0.25000000  -0.37500000  -0.50000000  1.0
     0.25000000  -0.12500000  -0.50000000  1.0
-    0.00000000   0.25000000  -0.25000000  1.0
-   -0.50000000  -0.50000000   0.25000000  1.0
-    0.00000000   0.12500000  -0.37500000  1.0
-   -0.25000000  -0.50000000   0.37500000  1.0
     0.25000000   0.12500000  -0.50000000  1.0
-    0.00000000   0.00000000  -0.50000000  1.0
-   -0.33333333   0.00000000   0.33333333  1.0
-    0.00000000   0.33333333   0.33333333  1.0
+    0.25000000   0.25000000  -0.37500000  1.0
     0.33333333   0.00000000   0.16666667  1.0
-    0.00000000   0.16666667   0.16666667  1.0
diff --git a/tests/test_data/Si-project/Si_super_deformed_castep/Si_211_unfold/easyunfold_sc_kpoints.cell b/tests/test_data/Si-project/Si_super_deformed_castep/Si_211_unfold/easyunfold_sc_kpoints.cell
@@ -12,30 +12,30 @@ Si  2.734364  2.734364  2.734364
 %ENDBLOCK positions_abs
 
 %BLOCK SPECTRAL_KPOINTS_LIST
+-0.5000000000 0.0000000000 0.0000000000
+-0.5000000000 0.2500000000 0.2500000000
+-0.4000000000 0.0000000000 0.0000000000
+-0.4000000000 0.3000000000 0.3000000000
+-0.3000000000 0.0000000000 0.0000000000
+-0.3000000000 0.3500000000 0.3500000000
+-0.2000000000 0.0000000000 0.0000000000
+-0.2000000000 0.4000000000 0.4000000000
+-0.1000000000 0.0000000000 0.0000000000
+-0.1000000000 0.4500000000 0.4500000000
+0.0000000000 -0.5000000000 -0.5000000000
+0.0000000000 -0.5000000000 0.0000000000
 0.0000000000 0.0000000000 0.0000000000
-0.1000000000 0.0000000000 0.0000000000
-0.1000000000 0.0500000000 0.0500000000
 0.0000000000 0.0500000000 0.0000000000
-0.2000000000 0.0000000000 0.0000000000
-0.2000000000 0.1000000000 0.1000000000
 0.0000000000 0.1000000000 0.0000000000
-0.3000000000 0.0000000000 0.0000000000
-0.3000000000 0.1500000000 0.1500000000
 0.0000000000 0.1500000000 0.0000000000
-0.4000000000 0.0000000000 0.0000000000
-0.4000000000 0.2000000000 0.2000000000
 0.0000000000 0.2000000000 0.0000000000
--0.5000000000 0.0000000000 0.0000000000
--0.5000000000 0.2500000000 0.2500000000
 0.0000000000 0.2500000000 0.0000000000
--0.4000000000 0.3000000000 0.3000000000
 0.0000000000 0.3000000000 0.0000000000
--0.3000000000 0.3500000000 0.3500000000
 0.0000000000 0.3500000000 0.0000000000
--0.2000000000 0.4000000000 0.4000000000
 0.0000000000 0.4000000000 0.0000000000
--0.1000000000 0.4500000000 0.4500000000
 0.0000000000 0.4500000000 0.0000000000
-0.0000000000 -0.5000000000 -0.5000000000
-0.0000000000 -0.5000000000 0.0000000000
+0.1000000000 0.0500000000 0.0500000000
+0.2000000000 0.1000000000 0.1000000000
+0.3000000000 0.1500000000 0.1500000000
+0.4000000000 0.2000000000 0.2000000000
 %ENDBLOCK SPECTRAL_KPOINTS_LIST
diff --git a/tests/test_data/Si-project/Si_super_deformed_castep/easyunfold_sc_kpoints.cell b/tests/test_data/Si-project/Si_super_deformed_castep/easyunfold_sc_kpoints.cell
@@ -12,30 +12,30 @@ Si  2.734364  2.734364  2.734364
 %ENDBLOCK positions_abs
 
 %BLOCK SPECTRAL_KPOINTS_LIST
+-0.5000000000 0.0000000000 0.0000000000
+-0.5000000000 0.2500000000 0.2500000000
+-0.4000000000 0.0000000000 0.0000000000
+-0.4000000000 0.3000000000 0.3000000000
+-0.3000000000 0.0000000000 0.0000000000
+-0.3000000000 0.3500000000 0.3500000000
+-0.2000000000 0.0000000000 0.0000000000
+-0.2000000000 0.4000000000 0.4000000000
+-0.1000000000 0.0000000000 0.0000000000
+-0.1000000000 0.4500000000 0.4500000000
+0.0000000000 -0.5000000000 -0.5000000000
+0.0000000000 -0.5000000000 0.0000000000
 0.0000000000 0.0000000000 0.0000000000
-0.1000000000 0.0000000000 0.0000000000
-0.1000000000 0.0500000000 0.0500000000
 0.0000000000 0.0500000000 0.0000000000
-0.2000000000 0.0000000000 0.0000000000
-0.2000000000 0.1000000000 0.1000000000
 0.0000000000 0.1000000000 0.0000000000
-0.3000000000 0.0000000000 0.0000000000
-0.3000000000 0.1500000000 0.1500000000
 0.0000000000 0.1500000000 0.0000000000
-0.4000000000 0.0000000000 0.0000000000
-0.4000000000 0.2000000000 0.2000000000
 0.0000000000 0.2000000000 0.0000000000
--0.5000000000 0.0000000000 0.0000000000
--0.5000000000 0.2500000000 0.2500000000
 0.0000000000 0.2500000000 0.0000000000
--0.4000000000 0.3000000000 0.3000000000
 0.0000000000 0.3000000000 0.0000000000
--0.3000000000 0.3500000000 0.3500000000
 0.0000000000 0.3500000000 0.0000000000
--0.2000000000 0.4000000000 0.4000000000
 0.0000000000 0.4000000000 0.0000000000
--0.1000000000 0.4500000000 0.4500000000
 0.0000000000 0.4500000000 0.0000000000
-0.0000000000 -0.5000000000 -0.5000000000
-0.0000000000 -0.5000000000 0.0000000000
+0.1000000000 0.0500000000 0.0500000000
+0.2000000000 0.1000000000 0.1000000000
+0.3000000000 0.1500000000 0.1500000000
+0.4000000000 0.2000000000 0.2000000000
 %ENDBLOCK SPECTRAL_KPOINTS_LIST
diff --git a/tests/test_data/Si-project/Si_super_deformed_soc/KPOINTS_easyunfold b/tests/test_data/Si-project/Si_super_deformed_soc/KPOINTS_easyunfold
@@ -1,28 +1,28 @@
 supercell kpoints
 25
 Rec
-    0.00000000   0.00000000   0.00000000  1.0
-   -0.50000000   0.25000000   0.25000000  1.0
-    0.00000000   0.25000000   0.00000000  1.0
+   -0.50000000  -0.50000000   0.25000000  1.0
+   -0.50000000  -0.12500000   0.37500000  1.0
    -0.50000000   0.00000000   0.00000000  1.0
-    0.00000000  -0.50000000  -0.50000000  1.0
-    0.00000000  -0.50000000   0.00000000  1.0
-    0.00000000   0.37500000  -0.37500000  1.0
+   -0.50000000   0.25000000   0.25000000  1.0
+   -0.33333333   0.00000000   0.33333333  1.0
    -0.25000000  -0.50000000   0.12500000  1.0
-   -0.50000000  -0.12500000   0.37500000  1.0
+   -0.25000000  -0.50000000   0.37500000  1.0
+   -0.25000000  -0.37500000  -0.50000000  1.0
    -0.25000000  -0.25000000  -0.12500000  1.0
+    0.00000000  -0.50000000  -0.50000000  1.0
+    0.00000000  -0.50000000   0.00000000  1.0
+    0.00000000   0.00000000  -0.50000000  1.0
+    0.00000000   0.00000000   0.00000000  1.0
+    0.00000000   0.12500000  -0.37500000  1.0
     0.00000000   0.12500000  -0.12500000  1.0
+    0.00000000   0.16666667   0.16666667  1.0
+    0.00000000   0.25000000  -0.25000000  1.0
+    0.00000000   0.25000000   0.00000000  1.0
+    0.00000000   0.33333333   0.33333333  1.0
+    0.00000000   0.37500000  -0.37500000  1.0
     0.25000000  -0.50000000   0.37500000  1.0
-    0.25000000   0.25000000  -0.37500000  1.0
-   -0.25000000  -0.37500000  -0.50000000  1.0
     0.25000000  -0.12500000  -0.50000000  1.0
-    0.00000000   0.25000000  -0.25000000  1.0
-   -0.50000000  -0.50000000   0.25000000  1.0
-    0.00000000   0.12500000  -0.37500000  1.0
-   -0.25000000  -0.50000000   0.37500000  1.0
     0.25000000   0.12500000  -0.50000000  1.0
-    0.00000000   0.00000000  -0.50000000  1.0
-   -0.33333333   0.00000000   0.33333333  1.0
-    0.00000000   0.33333333   0.33333333  1.0
+    0.25000000   0.25000000  -0.37500000  1.0
     0.33333333   0.00000000   0.16666667  1.0
-    0.00000000   0.16666667   0.16666667  1.0
diff --git a/tests/test_data/Si-project/Si_super_deformed_spin/KPOINTS_easyunfold b/tests/test_data/Si-project/Si_super_deformed_spin/KPOINTS_easyunfold
@@ -1,28 +1,28 @@
 supercell kpoints
 25
 Rec
-    0.00000000   0.00000000   0.00000000  1.0
-   -0.50000000   0.25000000   0.25000000  1.0
-    0.00000000   0.25000000   0.00000000  1.0
+   -0.50000000  -0.50000000   0.25000000  1.0
+   -0.50000000  -0.12500000   0.37500000  1.0
    -0.50000000   0.00000000   0.00000000  1.0
-    0.00000000  -0.50000000  -0.50000000  1.0
-    0.00000000  -0.50000000   0.00000000  1.0
-    0.00000000   0.37500000  -0.37500000  1.0
+   -0.50000000   0.25000000   0.25000000  1.0
+   -0.33333333   0.00000000   0.33333333  1.0
    -0.25000000  -0.50000000   0.12500000  1.0
-   -0.50000000  -0.12500000   0.37500000  1.0
+   -0.25000000  -0.50000000   0.37500000  1.0
+   -0.25000000  -0.37500000  -0.50000000  1.0
    -0.25000000  -0.25000000  -0.12500000  1.0
+    0.00000000  -0.50000000  -0.50000000  1.0
+    0.00000000  -0.50000000   0.00000000  1.0
+    0.00000000   0.00000000  -0.50000000  1.0
+    0.00000000   0.00000000   0.00000000  1.0
+    0.00000000   0.12500000  -0.37500000  1.0
     0.00000000   0.12500000  -0.12500000  1.0
+    0.00000000   0.16666667   0.16666667  1.0
+    0.00000000   0.25000000  -0.25000000  1.0
+    0.00000000   0.25000000   0.00000000  1.0
+    0.00000000   0.33333333   0.33333333  1.0
+    0.00000000   0.37500000  -0.37500000  1.0
     0.25000000  -0.50000000   0.37500000  1.0
-    0.25000000   0.25000000  -0.37500000  1.0
-   -0.25000000  -0.37500000  -0.50000000  1.0
     0.25000000  -0.12500000  -0.50000000  1.0
-    0.00000000   0.25000000  -0.25000000  1.0
-   -0.50000000  -0.50000000   0.25000000  1.0
-    0.00000000   0.12500000  -0.37500000  1.0
-   -0.25000000  -0.50000000   0.37500000  1.0
     0.25000000   0.12500000  -0.50000000  1.0
-    0.00000000   0.00000000  -0.50000000  1.0
-   -0.33333333   0.00000000   0.33333333  1.0
-    0.00000000   0.33333333   0.33333333  1.0
+    0.25000000   0.25000000  -0.37500000  1.0
     0.33333333   0.00000000   0.16666667  1.0
-    0.00000000   0.16666667   0.16666667  1.0