diff --git a/Manuscript/eDFT.tex b/Manuscript/eDFT.tex
index 3d68123..d3c5be7 100644
--- a/Manuscript/eDFT.tex
+++ b/Manuscript/eDFT.tex
@@ -331,6 +331,16 @@ c}\left[n\right]}{\partial w_K}
 \right|
 _{n=n_{\opGamma{\bw}}}.
 \eeq
+
+For implementation purposes, we will use in the rest of this work 
+(one-electron reduced) density matrices rather than Slater determinants
+as basic variables. If we denote ${\bmg}^{(K)}$  
+
+\beq
+\Gamma_{\mu\nu}^{(K)}=\sum_{p\in (K)}c_{\mu p}c_{\nu p}
+\eeq
+where the summation runs over the spin-orbitals that are occupied in
+$\Phi^{(K)}$. 
 %%%%%%%%%%%%%%%
 %\subsection{Hybrid GOK-DFT}
 %%%%%%%%%%%%%%%