diff --git a/src/function.cpp b/src/function.cpp
index 473a313838ec8589db82580bd7bcc5d078bf2549..29b8b456a897510f678f9b9fbe072f6872baa4f6 100644
--- a/src/function.cpp
+++ b/src/function.cpp
@@ -25,3 +25,9 @@ numerics::PolyWrapper numerics::functions::higher_parabola_1d =
     numerics::PolyWrapper({1., 0.0, -2.3, 0., -1.4});
 numerics::PolyWrapper numerics::functions::ref_polynomial_1d =
     numerics::PolyWrapper({1., -3., -1., 11., -17., 16., -4.});
+
+numerics::LennardJones numerics::functions::wide_LJ =
+    numerics::LennardJones(-4, 20);
+
+numerics::LennardJones numerics::functions::narrow_LJ =
+    numerics::LennardJones(-5, 3);