Added threshold_ordering parameter to CollinearMagneticStructureAnaly…

…zer in addition to PR #3574 (#3577)

* Modified ordering property of CollinearMagneticStructureAnalyzer to account for floating point imprecision, added test for that.

* improve CollinearMagneticStructureAnalyzer.ordering doc str, drop isclose in favor abs(tot_mag) > 1e-8

* compress tests/files/magnetic.example.CuO.mcif

* add comment with source DOI for mcif file

* link PR that added CuO AFM test

* Added treshold_ordering for determination of magnetic ordering in CollinearMagneticStructureAnalyzer.

* Added test case that demonstrates different ordering values dependent on threshold_ordering parameter.

* document default threshold_ordering, refactor test

---------

Co-authored-by: kueltzen <kueltzen@sv2218.zit.bam.de>
Co-authored-by: Janosh Riebesell <janosh.riebesell@gmail.com>

pymatgen/analysis/magnetism/analyzer.py

@@ -85,6 +85,7 @@ def __init__(
         set_net_positive: bool = True,
         threshold: float = 0,
         threshold_nonmag: float = 0.1,
+        threshold_ordering: float = 1e-8,
     ):
         """
         If magnetic moments are not defined, moments will be
@@ -132,6 +133,9 @@ def __init__(
             threshold_nonmag: number (in Bohr magneton)
                 below which nonmagnetic ions (with no magmom specified
                 in default_magmoms) will be rounded to zero
+            threshold_ordering: number (absolute of sum of all magmoms,
+                in Bohr magneton) below which total magnetization is treated as zero
+                when defining magnetic ordering. Defaults to 1e-8.
         """
         if default_magmoms:
             self.default_magmoms = default_magmoms
@@ -289,6 +293,7 @@ def __init__(
             structure = structure.get_primitive_structure(use_site_props=True)
 
         self.structure = structure
+        self.threshold_ordering = threshold_ordering
 
     @no_type_check  # ignore seemingly false mypy errors
     @staticmethod
@@ -483,7 +488,7 @@ def ordering(self) -> Ordering:
         """Applies heuristics to return a magnetic ordering for a collinear
         magnetic structure. Result is not guaranteed to be correct, just a best
         guess. Tolerance for minimum total magnetization to be considered
-        ferro/ferrimagnetic is 1e-8.
+        ferro/ferrimagnetic is self.threshold_ordering and defaults to 1e-8.
 
         Returns:
             Ordering: Enum  with values FM: ferromagnetic, FiM: ferrimagnetic,
@@ -508,9 +513,9 @@ def ordering(self) -> Ordering:
 
         is_potentially_ferromagnetic = np.all(magmoms >= 0) or np.all(magmoms <= 0)
 
-        if abs(total_magnetization) > 1e-8 and is_potentially_ferromagnetic:
+        if abs(total_magnetization) > self.threshold_ordering and is_potentially_ferromagnetic:
             return Ordering.FM
-        if abs(total_magnetization) > 1e-8:
+        if abs(total_magnetization) > self.threshold_ordering:
             return Ordering.FiM
         if max_magmom > 0:
             return Ordering.AFM

tests/analysis/magnetism/test_analyzer.py

@@ -189,8 +189,9 @@ def test_magnetic_properties(self):
         assert mag_struct_analyzer.get_exchange_group_info() == ("Fm-3m", 225)
 
         # https://github.com/materialsproject/pymatgen/pull/3574
-        mag_struct_analyzer = CollinearMagneticStructureAnalyzer(self.CuO_expt)
-        assert mag_struct_analyzer.ordering == Ordering.AFM
+        for threshold, expected in [(1e-8, Ordering.AFM), (1e-20, Ordering.FiM)]:
+            mag_struct_analyzer = CollinearMagneticStructureAnalyzer(self.CuO_expt, threshold_ordering=threshold)
+            assert mag_struct_analyzer.ordering == expected
 
     def test_str(self):
         msa = CollinearMagneticStructureAnalyzer(self.NiO_AFM_001)