Merge pull request #37847 from mantidproject/crystal-field-mag-bug

Correct bug of missing 'Hmag' field in CrystalField interface

docs/source/release/v6.11.0/Direct_Geometry/CrystalField/Bugfixes/37847.rst

@@ -0,0 +1,2 @@
+- The method `cf.getMagneticMoment()` no longer ignores the `Hmag` field, which is now
+  correctly considered in the calculations of the magnetic moment.

scripts/Inelastic/CrystalField/function.py

@@ -702,7 +702,7 @@ def toString(self):
                 out += ",Temperature=%s" % (self._physpropTemperature)
             else:  # either susceptibility or M(T)
                 out += ",inverse=%s" % (1 if self._suscInverseFlag else 0)
-                out += (",Hmag=%s" % (self._hmag)) if self._typeid == self.MAGNETISATION else ""
+                out += (",Hmag=%s" % (self._hmag)) if self._typeid == self.MAGNETICMOMENT else ""
                 if self._typeid == self.SUSCEPTIBILITY and self._lambda != 0:
                     out += ",Lambda=%s" % (self._lambda)
                 if self._typeid == self.SUSCEPTIBILITY and self._chi0 != 0:

scripts/test/CrystalFieldTest.py

@@ -675,6 +675,16 @@ def test_api_CrystalField_physical_properties(self):
         self.assertAlmostEqual(chi_powder[10] * 10, 1 / invmt_powder_SI[10], 2)
         self.assertAlmostEqual(chi_powder[15] * 10, 1 / invmt_powder_SI[15], 2)
 
+        # Test different Hmag
+        _, h_mag_10 = cf.getMagneticMoment(Hmag=10, Temperature=np.linspace(1, 300, 50), Hdir="powder", Unit="bohr")
+        self.assertAlmostEqual(h_mag_10[5], 0.323607, 5)
+        self.assertAlmostEqual(h_mag_10[10], 0.182484, 5)
+        self.assertAlmostEqual(h_mag_10[15], 0.129909, 5)
+        _, h_mag_5 = cf.getMagneticMoment(Hmag=5, Temperature=np.linspace(1, 300, 50), Hdir="powder", Unit="bohr")
+        self.assertAlmostEqual(h_mag_5[5], 0.16923426, 6)
+        self.assertAlmostEqual(h_mag_5[10], 0.09228022, 6)
+        self.assertAlmostEqual(h_mag_5[15], 0.06525625, 6)
+
         # Test M(H) calculations
         Hmag_SI, mag_SI = cf.getMagneticMoment(np.linspace(0, 30, 15), Temperature=10, Hdir=[0, 1, -1], Unit="SI")
         self.assertAlmostEqual(mag_SI[1], 1.8139, 3)