diff --git a/src/polykin/thermo/acm/ideal.py b/src/polykin/thermo/acm/ideal.py
index 5bf0046..710b932 100644
--- a/src/polykin/thermo/acm/ideal.py
+++ b/src/polykin/thermo/acm/ideal.py
@@ -12,13 +12,15 @@
 
 
 class IdealSolution(ActivityCoefficientModel):
-    r"""Ideal solution model."""
+    r"""Ideal solution model.
+
+    $$ g^{E} = 0 $$
+
+    """
 
     def gE(self, T: float, x: FloatVector) -> float:
         r"""Molar excess Gibbs energy, $g^{E}$.
 
-        $$ g^{E} = 0 $$
-
         Parameters
         ----------
         T : float