fix issue with phi

RapportStage/Rapport.tex

@@ -391,6 +391,7 @@ The MP$n$ energy is defined as
 	E_{\text{MP}n}= \sum_{k=0}^n E^{(k)},
 \end{equation}
 where $E^{(k)}$ is the $k$th-order correction.
+\titou{$n$ is the number of electrons and here you use it as something else...}
 The MP0 energy overestimates the energy by double counting the electron-electron interaction and is equal to the sum of the occupied orbital energies, i.e.,
 \begin{equation}
 	E_{\text{MP0}} = \sum_i^n \epsilon_i.