Add optional Moore Labels to AtomcTermSymbol

docs/source/states.rst

@@ -140,6 +140,16 @@ J must satisfy the "triangle rule" (\|L-S\| ≤ J ≤ L+S); if this test fails,
       ...
     pyvalem.states.atomic_term_symbol.AtomicTermSymbolError: Invalid atomic term symbol: 3P_3 |L-S| <= J <= L+S must be satisfied.
 
+A single, lowercase letter label to distinguish term symbols with the same ``S``, ``L`` that arise from the same atomic configuration; the convention assumed to be followed is that of C. E. Moore, NBS Circ, No. 488 (1950). See e.g. G. Nave et al., Astrophys. J. Suppl. Ser. 94:221-459 (1994). Terms with the same ``S`` and ``L`` of even parity are labelled in order of increasing energy as ``a``, ``b``, etc.; terms with odd parity are labelled in order of increasing energy as ``z``, ``y``, ``x``, etc.
+
+.. code-block:: pycon
+
+    >>> from pyvalem.states import AtomicTermSymbol
+    >>> a0 = AtomicTermSymbol('a5D')
+    >>> a1 = AtomicTermSymbol('b5D')
+    >>> a2 = AtomicTermSymbol('z3Po')
+    >>> a3 = AtomicTermSymbol('y3Po')
+
 
 ``DiatomicMolecularConfiguration``
 ==================================

src/pyvalem/states/atomic_term_symbol.py

@@ -13,14 +13,20 @@
 
 integer = pp.Word(pp.nums)
 
+# The single, lowercase letter label given in the Multiplet Table of C. E. Moore
+# NBS Circ, No. 488 (1950) and sometimes used to distinguish terms with the same
+# S, L from the same configuration. See e.g. G. Nave et al., Astrophys. J. Suppl. Ser.
+# 94:221-459 (1994).
+moore_label = pp.Char("abcdefghijklmnopqrstuvwxyz").setResultsName("moore_label")
 atom_Smult = integer.setResultsName("Smult")
 atom_Lletter = pp.oneOf(atom_L_symbols).setResultsName("Lletter")
 atom_Jstr = (
     integer + pp.Optional(pp.Suppress("/") + "2") + pp.StringEnd()
 ).setResultsName("Jstr")
 atom_parity = pp.Literal("o").setResultsName("parity")
 atom_term = (
-    atom_Smult
+    pp.Optional(moore_label)
+    + atom_Smult
     + atom_Lletter
     + pp.Optional(atom_parity)
     + pp.Optional(pp.Suppress("_") + atom_Jstr)
@@ -41,6 +47,7 @@ def __init__(self, state_str):
         self.L = None
         self.parity = None
         self.J = None
+        self.moore_letter = ""
         self._parse_state(state_str)
 
     def _parse_state(self, state_str):
@@ -55,6 +62,7 @@ def _parse_state(self, state_str):
         self.Lletter = components.Lletter
         self.L = atom_L_symbols.index(components.Lletter)
         self.parity = components.get("parity")
+        self.moore_label = components.get("moore_label", "")
         try:
             self.J = parse_fraction(components.Jstr)
         except ValueError as err:
@@ -77,7 +85,11 @@ def _validate_j(self):
 
     @property
     def html(self):
-        html_chunks = ["<sup>{0:d}</sup>{1:s}".format(self.Smult, self.Lletter)]
+        html_chunks = [
+            "{0}<sup>{1:d}</sup>{2:s}".format(
+                self.moore_letter, self.Smult, self.Lletter
+            )
+        ]
         if self.parity:
             html_chunks.append("<sup>o</sup>")
         if self.J is not None:
@@ -87,7 +99,11 @@ def html(self):
 
     @property
     def latex(self):
-        latex_chunks = [r"{{}}^{{{}}}\mathrm{{{}}}".format(self.Smult, self.Lletter)]
+        latex_chunks = [
+            r"{}{{}}^{{{}}}\mathrm{{{}}}".format(
+                self.moore_letter, self.Smult, self.Lletter
+            )
+        ]
         if self.parity:
             latex_chunks.append("^o")
         if self.J is not None:

tests/test_atomic_term_symbols.py

@@ -51,6 +51,17 @@ def test_atomic_term_symbol_equality(self):
         self.assertEqual(a0, a1)
         self.assertNotEqual(a0, a2)
 
+    def test_moore_label(self):
+        a0 = AtomicTermSymbol("a5D")
+        a1 = AtomicTermSymbol("z3Po")
+        a2 = AtomicTermSymbol("2F")
+        a3 = AtomicTermSymbol("e5D_4")
+        self.assertEqual(a0.moore_label, "a")
+        self.assertEqual(a1.moore_label, "z")
+        self.assertEqual(a2.moore_label, "")
+        self.assertEqual(a3.moore_label, "e")
+        self.assertRaises(AtomicTermSymbolError, AtomicTermSymbol, "A5D")
+
 
 if __name__ == "__main__":
     unittest.main()

tests/test_stateful_species.py

@@ -13,6 +13,7 @@
 class StatefulSpeciesTest(unittest.TestCase):
     def test_stateful_species_parsing(self):
         _ = StatefulSpecies("Ar *")
+        _ = StatefulSpecies("Fe e5G")
         _ = StatefulSpecies("CrH 1sigma2.2sigma1.1pi4.3sigma1; 6SIGMA+")
         _ = StatefulSpecies("H(35Cl) J=2")
         _ = StatefulSpecies("OH X(2Π_1/2, J=2")
@@ -104,6 +105,13 @@ def test_stateful_species_key_value_pair_ordering(self):
         ss1 = StatefulSpecies("H n=3;l=1")
         self.assertEqual(repr(ss1), "H n=3;l=1")
 
+    def test_atomic_term_symbols(self):
+        ss1 = StatefulSpecies("Fe+ a3D")
+        self.assertEqual(ss1.states[0].moore_label, "a")
+        self.assertEqual(ss1.states[0].S, 1)
+
+        self.assertRaises(StateParseError, StatefulSpecies, "Ti +2 A5D")
+
 
 if __name__ == "__main__":
     unittest.main()