diff --git a/doc/src/Eqs/pair_multi_lucy.jpg b/doc/src/Eqs/pair_multi_lucy.jpg
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diff --git a/doc/src/Eqs/pair_multi_lucy.tex b/doc/src/Eqs/pair_multi_lucy.tex
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+\documentstyle[12pt]{article}
+
+\begin{document}
+
+$$
+ F_{i}^{DD}(\rho_i,\rho_j,r_{ij}) = \frac{1}{2} \omega_{DD}\left(r_{ij}\right) 
+                       \left[A\left(\rho_i\right) + A\left(\rho_j\right)\right]e_{ij} 
+$$
+
+\end{document}
diff --git a/doc/src/Eqs/pair_multi_lucy2.jpg b/doc/src/Eqs/pair_multi_lucy2.jpg
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diff --git a/doc/src/Eqs/pair_multi_lucy2.tex b/doc/src/Eqs/pair_multi_lucy2.tex
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+\documentstyle[12pt]{article}
+
+\begin{document}
+
+$$
+ \omega_{DD}\left(r_{ij}\right) = \left(1+\frac{3r_{ij}}{r_{cut}}\right)\left(1+\frac{r_{ij}}{r_{cut}}\right)^3
+$$
+
+\end{document}
diff --git a/doc/src/Eqs/pair_multi_lucy_energy.jpg b/doc/src/Eqs/pair_multi_lucy_energy.jpg
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diff --git a/doc/src/Eqs/pair_multi_lucy_energy.tex b/doc/src/Eqs/pair_multi_lucy_energy.tex
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+\documentstyle[12pt]{article}
+
+\begin{document}
+
+$$
+ u_{i}^{DD}\left(\rho_{i}\right) = \frac{\pi r_{cut}^4}{84} \int_{\rho_0}^{\rho_i} A\left(\rho^{'}\right) d\rho^{'}
+$$
+
+\end{document}