diff --git a/doc/Eqs/pair_lj_cubic.jpg b/doc/Eqs/pair_lj_cubic.jpg
index e52392b87e..a5ff3de22c 100644
Binary files a/doc/Eqs/pair_lj_cubic.jpg and b/doc/Eqs/pair_lj_cubic.jpg differ
diff --git a/doc/Eqs/pair_lj_cubic.tex b/doc/Eqs/pair_lj_cubic.tex
index bb4ea9c589..e2e1b67dd7 100644
--- a/doc/Eqs/pair_lj_cubic.tex
+++ b/doc/Eqs/pair_lj_cubic.tex
@@ -4,7 +4,7 @@
 
 \begin{eqnarray*}
  E &=& u_{LJ}(r) \qquad r \leq r_s \\
-    &=&  u_{LJ}(r_s) + (r-r_s) u'_{LJ}(r) - \frac{1}{6} A_3 (r-r_s)^3 \qquad r_s < r \leq r_c \\
+    &=&  u_{LJ}(r_s) + (r-r_s) u'_{LJ}(r_s) - \frac{1}{6} A_3 (r-r_s)^3 \qquad r_s < r \leq r_c \\
     &=& 0 \qquad r > r_c 
 \end{eqnarray*}