Fix: make cell and structure backwards compatible

src/py4vasp/_data/contcar.py

@@ -76,10 +76,17 @@ def _topology(self):
 
 
 def _cell_lines(cell):
-    yield _float_format(cell.scale, scientific=False).lstrip()
+    yield _float_format(_cell_scale(cell.scale), scientific=False).lstrip()
     yield from _vectors_to_lines(cell.lattice_vectors)
 
 
+def _cell_scale(scale):
+    if not scale.is_none():
+        return scale[()]
+    else:
+        return 1.0
+
+
 def _ion_position_lines(positions, selective_dynamics):
     if selective_dynamics.is_none():
         yield from _vectors_to_lines(positions)
@@ -92,7 +99,8 @@ def _lattice_velocity_lines(velocities, cell):
         return
     yield "Lattice velocities and vectors"
     yield from _vectors_to_lines(velocities, scientific=True)
-    yield from _vectors_to_lines(cell.scale * cell.lattice_vectors, scientific=True)
+    lattice_vectors = _cell_scale(cell.scale) * cell.lattice_vectors
+    yield from _vectors_to_lines(lattice_vectors, scientific=True)
 
 
 def _ion_velocity_lines(velocities):

src/py4vasp/_data/structure.py

@@ -101,7 +101,7 @@ def _create_repr(self, format_=_Format()):
         step = self._get_last_step()
         lines = (
             format_.comment_line(self._topology(), self._step_string()),
-            format_.scaling_factor(self._raw_data.cell.scale),
+            format_.scaling_factor(self._scale()),
             format_.vectors_to_table(self._raw_data.cell.lattice_vectors[step]),
             format_.ion_list(self._topology()),
             format_.coordinate_system(),
@@ -288,7 +288,13 @@ def _topology(self):
 
     def _lattice_vectors(self):
         lattice_vectors = _LatticeVectors(self._raw_data.cell.lattice_vectors)
-        return self._raw_data.cell.scale * lattice_vectors[self._get_steps()]
+        return self._scale() * lattice_vectors[self._get_steps()]
+
+    def _scale(self):
+        if not self._raw_data.cell.scale.is_none():
+            return self._raw_data.cell.scale[()]
+        else:
+            return 1.0
 
     def _positions(self):
         return self._raw_data.positions[self._get_steps()]
@@ -341,7 +347,8 @@ def error_message(self, key, err):
 
 
 def _cell_from_ase(structure):
-    return raw.Cell(lattice_vectors=np.array([structure.get_cell()]))
+    lattice_vectors = np.array([structure.get_cell()])
+    return raw.Cell(lattice_vectors, scale=raw.VaspData(1.0))
 
 
 def _replace_or_set_elements(poscar, elements):

src/py4vasp/_raw/data.py

@@ -82,7 +82,7 @@ class Cell:
 
     lattice_vectors: VaspData
     "Lattice vectors defining the unit cell."
-    scale: float = 1.0
+    scale: float
     "Global scaling factor applied to all lattice vectors."
 
 

src/py4vasp/_raw/definition.py

@@ -71,7 +71,6 @@ def selections(quantity):
 #
 schema.add(
     raw.Cell,
-    required=raw.Version(6, 5),
     scale="intermediate/ion_dynamics/scale",
     lattice_vectors="intermediate/ion_dynamics/lattice_vectors",
 )

tests/conftest.py

@@ -607,7 +607,7 @@ def _Sr2TiO4_born_effective_charges():
 
 
 def _Sr2TiO4_cell():
-    scale = 6.9229
+    scale = raw.VaspData(6.9229)
     lattice_vectors = [
         [1.0, 0.0, 0.0],
         [0.678112209738693, 0.734958387251008, 0.0],
@@ -743,7 +743,8 @@ def _Fe3O4_cell():
         [-1.3633791448, 0.0, 5.0446102592],
     ]
     scaling = np.linspace(0.98, 1.01, number_steps)
-    return raw.Cell(lattice_vectors=np.multiply.outer(scaling, lattice_vectors))
+    lattice_vectors = np.multiply.outer(scaling, lattice_vectors)
+    return raw.Cell(lattice_vectors, scale=raw.VaspData(None))
 
 
 def _Fe3O4_CONTCAR():
@@ -853,7 +854,7 @@ def _Fe3O4_velocity():
 
 def _Ca3AsBr3_cell():
     return raw.Cell(
-        scale=5.93,
+        scale=raw.VaspData(5.93),
         lattice_vectors=_make_data(np.eye(3)),
     )
 

tests/data/test_structure.py

@@ -83,8 +83,11 @@ def Ca3AsBr3(raw_data):
 def make_structure(raw_structure):
     structure = Structure.from_data(raw_structure)
     structure.ref = types.SimpleNamespace()
-    cell = raw_structure.cell
-    structure.ref.lattice_vectors = cell.scale * cell.lattice_vectors
+    if not raw_structure.cell.scale.is_none():
+        scale = raw_structure.cell.scale[()]
+    else:
+        scale = 1.0
+    structure.ref.lattice_vectors = scale * raw_structure.cell.lattice_vectors
     structure.ref.positions = raw_structure.positions
     return structure