added DOF warnings

ramannoodle/exceptions.py

@@ -26,6 +26,13 @@ def __init__(self, reason: str):
         pass
 
 
+class DOFWarning(UserWarning):
+    """Used when something may be wrong with a DOF."""
+
+    def __init__(self, reason: str):
+        pass
+
+
 class SymmetryException(Exception):
     """Raised when something goes wrong with an operation involving symmetry."""
 

ramannoodle/polarizability/interpolation.py

@@ -6,6 +6,7 @@
 
 from pathlib import Path
 import copy
+from warnings import warn
 
 import numpy as np
 from numpy.typing import NDArray
@@ -24,7 +25,7 @@
 
 from .. import io
 from ..io.io_utils import pathify_as_list
-from ..exceptions import verify_ndarray_shape
+from ..exceptions import verify_ndarray_shape, DOFWarning
 
 
 def get_amplitude(
@@ -215,6 +216,20 @@ def _construct_and_add_interpolations(
                     f"due to symmetry, amplitude {duplicate} should not be specified"
                 )
 
+            # Warn user if amplitudes don't span zero
+            max_amplitude = np.max(interpolation_x)
+            min_amplitude = np.min(interpolation_x)
+            if np.isclose(max_amplitude, 0, atol=1e-3).all() or max_amplitude <= 0:
+                warn(
+                    "max amplitude <= 0, when usually it should be > 0",
+                    DOFWarning,
+                )
+            if np.isclose(min_amplitude, 0, atol=1e-3).all() or min_amplitude >= 0:
+                warn(
+                    "min amplitude >= 0, when usually it should be < 0",
+                    DOFWarning,
+                )
+
             if len(interpolation_x) <= interpolation_order:
                 raise InvalidDOFException(
                     f"insufficient points ({len(interpolation_x)}) available for "