diff --git a/docs/conf.py b/docs/conf.py
index 6f2394e2..4f85b52d 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -70,12 +70,14 @@
 # -- Custom extension of Sphinx ----------------------------------------------
 from docutils import nodes
 
+
 # defines an INCAR tag
 def tag_role(name, rawtext, text, lineno, inliner, options={}, content=[]):
     url = f"https://www.vasp.at/wiki/index.php/{text}"
     node = nodes.reference(rawtext, text, refuri=url, **options)
     return [node], []
 
+
 def setup(app):
-    app.add_role('tag', tag_role)
-    return
\ No newline at end of file
+    app.add_role("tag", tag_role)
+    return
diff --git a/src/py4vasp/_combine/base.py b/src/py4vasp/_combine/base.py
index 323193a6..3672a4b5 100644
--- a/src/py4vasp/_combine/base.py
+++ b/src/py4vasp/_combine/base.py
@@ -4,7 +4,7 @@
 import pathlib
 from typing import Dict, List
 
-from py4vasp import exception, calculation
+from py4vasp import calculation, exception
 
 
 def _match_combine_with_refinement(combine_name: str):
diff --git a/src/py4vasp/calculation/__init__.py b/src/py4vasp/calculation/__init__.py
index e4cfd630..b82f9946 100644
--- a/src/py4vasp/calculation/__init__.py
+++ b/src/py4vasp/calculation/__init__.py
@@ -1,6 +1,6 @@
 # Copyright © VASP Software GmbH,
 # Licensed under the Apache License 2.0 (http://www.apache.org/licenses/LICENSE-2.0)
-'''Provide refinement functions for a the raw data of a VASP calculation run in the
+"""Provide refinement functions for a the raw data of a VASP calculation run in the
 current directory.
 
 Usually one is not directly interested in the raw data that is produced but
@@ -37,8 +37,9 @@ class provides a more flexible interface with which you can determine the source
 >>> calc.dos.read()
 
 In the latter example, you can change the path from which the data is extracted.
-'''
+"""
 import importlib
+
 from py4vasp import exception
 from py4vasp._util import convert
 
@@ -75,6 +76,7 @@ class provides a more flexible interface with which you can determine the source
 )
 _private = ("dispersion",)
 
+
 def __getattr__(attr):
     if attr in (__all__ + _private):
         module = importlib.import_module(f"py4vasp.calculation._{attr}")
diff --git a/src/py4vasp/calculation/_density.py b/src/py4vasp/calculation/_density.py
index bf08177e..3260d36b 100644
--- a/src/py4vasp/calculation/_density.py
+++ b/src/py4vasp/calculation/_density.py
@@ -2,8 +2,8 @@
 # Licensed under the Apache License 2.0 (http://www.apache.org/licenses/LICENSE-2.0)
 import numpy as np
 
-from py4vasp import calculation, exception, _config
-from py4vasp._util import import_, documentation, index, select
+from py4vasp import _config, calculation, exception
+from py4vasp._util import documentation, import_, index, select
 from py4vasp.calculation import _base, _structure
 
 pretty = import_.optional("IPython.lib.pretty")
@@ -63,7 +63,7 @@ class Density(_base.Refinery, _structure.Mixin):
     def __str__(self):
         _raise_error_if_no_data(self._raw_data.charge)
         grid = self._raw_data.charge.shape[1:]
-        topology =  calculation.topology.from_data(self._raw_data.structure.topology)
+        topology = calculation.topology.from_data(self._raw_data.structure.topology)
         if self._selection == "tau":
             name = "Kinetic energy"
         elif self.is_nonpolarized():
diff --git a/src/py4vasp/calculation/_potential.py b/src/py4vasp/calculation/_potential.py
index 49abd2b2..dbc92b06 100644
--- a/src/py4vasp/calculation/_potential.py
+++ b/src/py4vasp/calculation/_potential.py
@@ -4,7 +4,7 @@
 
 import numpy as np
 
-from py4vasp import calculation, exception, _config
+from py4vasp import _config, calculation, exception
 from py4vasp._util import select
 from py4vasp.calculation import _base, _structure
 
diff --git a/tests/analysis/test_mlff.py b/tests/analysis/test_mlff.py
index 12f44293..6439de0f 100644
--- a/tests/analysis/test_mlff.py
+++ b/tests/analysis/test_mlff.py
@@ -8,7 +8,7 @@
 import numpy as np
 import pytest
 
-from py4vasp import exception, calculation
+from py4vasp import calculation, exception
 from py4vasp._analysis.mlff import MLFFErrorAnalysis
 
 
diff --git a/tests/calculation/test_density.py b/tests/calculation/test_density.py
index 50d3de12..2cdf5d80 100644
--- a/tests/calculation/test_density.py
+++ b/tests/calculation/test_density.py
@@ -6,7 +6,7 @@
 import numpy as np
 import pytest
 
-from py4vasp import calculation, exception, raw, _config
+from py4vasp import _config, calculation, exception, raw
 from py4vasp._third_party.viewer import viewer3d
 
 
diff --git a/tests/calculation/test_potential.py b/tests/calculation/test_potential.py
index 40eaede4..a3d63ce8 100644
--- a/tests/calculation/test_potential.py
+++ b/tests/calculation/test_potential.py
@@ -6,7 +6,7 @@
 import numpy as np
 import pytest
 
-from py4vasp import calculation, exception, raw, _config
+from py4vasp import _config, calculation, exception, raw
 from py4vasp._third_party.viewer import viewer3d
 
 
diff --git a/tests/calculation/test_repr.py b/tests/calculation/test_repr.py
index 12a9d3fe..19e24d78 100644
--- a/tests/calculation/test_repr.py
+++ b/tests/calculation/test_repr.py
@@ -1,6 +1,7 @@
 # Copyright © VASP Software GmbH,
 # Licensed under the Apache License 2.0 (http://www.apache.org/licenses/LICENSE-2.0)
 import importlib
+
 from py4vasp import calculation
 from py4vasp._util import convert