updated YAML instructions in reactions.rst

doc/sphinx/yaml/reactions.rst

@@ -439,17 +439,20 @@ Additional fields are:
     ``eig0``
         The absolute value of the least negative chemically significant eigenvalue of
         the master equation for the :math:`i^{th}` collider (when pure), evaluated at
-        the low-pressure limit, :math:`\Lambda_{0,i}(T)[M]`. This parameter is entered
-        in modified Arrhenius format to enable consideration of temperature dependence.
+        the low-pressure limit, :math:`\Lambda_{0,i}(T)[M]`. The user must explicitly
+        assign an ``eig0`` for ``M``. This parameter is entered in modified Arrhenius
+        format to enable consideration of temperature dependence.
 
     ``efficiency``
         The third-body efficiency of the collider relative to that of the reference
         collider ``M``, defined as :math:`\epsilon_{0,i}(T)=\Lambda_{0,i}(T)/\Lambda_{0,\text{M}}(T)`.
         The user does not need to assign an ``efficiency`` for ``M``, as it is always
-        equal to 1 by definition. This parameter is entered in modified Arrhenius format
-        to enable consideration of temperature dependence. If the user wishes to specify
-        a temperature-independent value, then ``A`` can be set to this value and ``b``
-        and ``Ea`` can be set to 0.
+        equal to 1 by definition. However, they are free to do so, as long as it takes
+        the form 'efficiency: {A: 1, b: 0, Ea: 0}' (no other variations are permitted).
+        This parameter is entered in modified Arrhenius format to enable consideration
+        of temperature dependence. If the user wishes to specify a
+        temperature-independent value, then ``A`` can be set to this value and ``b`` and
+        ``Ea`` can be set to 0 (such as 'H2O: {A: 10, b: 0, Ea: 0}').
 
     A :ref:`Troe <sec-yaml-falloff>` implementation also requires: ``high-P-rate-constant``,
     ``low-P-rate-constant``, ``Troe`` (do not use the Troe ``efficiencies`` key).
@@ -479,7 +482,7 @@ Examples:
 
 *`linear-Burke` rate with PLOG format for the reference collider (Ar)*:
 
-    equation: H + O2 (+M) <=> HO2 (+M)
+    equation: H + O2 (+M) <=> HO2 (+M) # Adding '(+M)' is optional
     type: linear-Burke
     colliders:
     - name: M