+For defects far away from each other the formation energy of the defect combination should approximately become the sum of the formation energies of the individual defects.
+The interaction of such defects is low resulting in $E=0$.
+In fact, for another \hkl<0 0 -1> dumbbell interstitial created at position $\frac{a_{\text{Si}}}{2}\hkl<3 2 3>$ relative to the initial one an energy of \ldots eV is obtained.
+Configurations wih energies greater than zero are energetically unfavorable and expose a repulsive interaction.
+These configurations are unlikely to arise or to persist for non-zero temperatures.
+Energies below zero indicate configurations favored compared to configurations in which these point defects are separated far away from each other.
+
+Investigating the first part of table \ref{tab:defects:e_of_comb}, namely the combinations with another \hkl<1 0 0>-type interstitial, most of the combinations result in energies below zero.
+Surprisingly the most favorable configurations are the ones with the second defect created at the very next silicon neighbour and a change in orientation compared to the initial one.
+\begin{figure}[h]
+\caption{}
+\label{fig:defects:comb_db_01}
+\end{figure}
+Figure \ref{} shows the structure of these two configurations.
+
+
+
+