\begin{figure}[!h]
\begin{center}
\includegraphics[width=8cm]{unit_cell.eps}
- \caption{Insertion positions for the tetrahedral (${\color{red}\bullet}$), hexagonal (${\color{green}\bullet}$) and <110> dumbbell (${\color{purple}\bullet}$) interstitial configuration.}
+ \caption{Insertion positions for the tetrahedral (${\color{red}\bullet}$), hexagonal (${\color{green}\bullet}$) and <110> dumbbell (${\color{magenta}\bullet}$) interstitial configuration.}
\end{center}
\end{figure}
To investigate the intesrtitial configurations of C and Si in Si, a simulation volume of 9 silicon unit cells in each direction is used.
The temperature is set to $T=0\, K$.
-The insertion positions are illustrated in Fig 2.
-In separated simulation runs a carbon and a silicon atom respectively is inserted at the tetrahedral $(0,0,0)$ (${\color{red}\bullet}$), hexagonal $(-1/8,-1/8,1/8)$ (${\color{green}\bullet}$), supposed dumbbell $(-1/8,-1/8)$ (${\color{purple}\bullet}$) and at random positions (in units of the silicon lattice constant) where the origin is located in the middle of the unit cell.
-In order to avoid too high kinetic energies in the case of the dumbbell configuration the nearest silicon neighbour atom is shifted to $(-1/4,-1/4,-1/4)$ ($\circ$).
+The insertion positions are illustrated in Fig. 2.
+In separated simulation runs a carbon and a silicon atom respectively is inserted at the tetrahedral $(0,0,0)$ (${\color{red}\bullet}$), hexagonal $(-1/8,-1/8,1/8)$ (${\color{green}\bullet}$), supposed dumbbell $(-1/8,-1/8,-1/4)$ (${\color{magenta}\bullet}$) and at random positions (in units of the silicon lattice constant) where the origin is located in the middle of the unit cell.
+In order to avoid too high kinetic energies in the case of the dumbbell configuration the nearest silicon neighbour atom is shifted to $(-3/8,-3/8,-1/4)$ ($\circ$).
The introduced kinetic energy is scaled out by a relaxation time of $2\, ps$.
The same volume is used to investigate diffusion.
\caption{Diffusion constants}
\end{center}
\end{figure}
-The influence of interstitials on the diffusion of a single carbon atom is displayed in Fig. 4.
+The influence of interstitials on the diffusion of a single carbon atom is displayed in Fig. 3.
\ldots
Carbon atoms are introduced into the whole simulation volume (red), the region which corresponds to the size of a minimal SiC precipitation (green) and the volume which contains the necessary amount of silicon for a minimal precipitation (blue).}
\end{center}
\end{figure}
-Fig. 5 shows results of the simulation runs targeting the observation of a precipitation event.
+Fig. 4 shows results of the simulation runs targeting the observation of a precipitation event.
The C-C pair correlation function suggests carbon nucleation for the simulation runs where carbon was inserted into the two smaller regions.
The peak at $1.5\, \textrm{\AA}$ fits quite well the next neighbour distance of diamond.
On the other hand the Si-C pair correlation function indicates formation of SiC bonds with an increased crystallinity for the simulation in which carbon is inserted into the whole simulation volume.