\label{eq:defects:e_of_comb}
\end{equation}
with $E_{\text{f}}^{\text{defect combination}}$ being the formation energy of the defect combination, $E_{\text{f}}^{\text{C \hkl<0 0 -1> dumbbell}}$ being the formation energy of the C \hkl<0 0 -1> dumbbell interstitial defect and $E_{\text{f}}^{\text{2nd defect}}$ being the formation energy of the second defect.
-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.
+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 with zero interaction resulting in $E=0$.
+In fact, for another \hkl<0 0 -1> dumbbell interstitial created at position $\frac{a_{\text{Si}}}{2}\hkl<3 2 3>$ ($\approx 10.2$ \AA) and $\frac{a_{\text{Si}}}{2}\hkl<2 3 2>$ ($\approx 12.8$ \AA, maximum distance due to periodic boundary conditions) relative to the initial one an energy of -0.19 eV and ... 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.
but better ...
-1.88 and -1.38 ...
+Minimum E (reorientation) per distance
+
+Todo: Si int and C sub ...
+Todo: Model of kick-out and kick-in mechnism?
+
+Todo: Jahn-Teller distortion (vacancy) $\rightarrow$ actually three possibilities! :(