}
\includegraphics[width=6cm]{c_00-1_0-10_mig_vasp.ps}
+ \includegraphics[width=6cm]{c_00-1_0-10_mig_dis_vasp.ps}
\end{slide}
\end{slide}
+\begin{slide}
+
+ {\large\bf\boldmath
+ Carbon point defects in silicon
+ }
+
+ \begin{minipage}{3.2cm}
+ \underline{C tetrahedral}\\
+ Relaxes into \hkl<0 0 1> configuration\\[0.2cm]
+ \underline{C hexagonal}\\
+ Relaxes into \hkl<0 0 1> configuration\\[0.4cm]
+ \underline{\hkl<1 1 0> interstitial}
+ \begin{itemize}
+ \item $E_{\text{f}}=3.60\text{ eV}$
+ \end{itemize}
+ \includegraphics[width=3cm]{c_pd_vasp/110_2333.eps}
+ \end{minipage}
+ \begin{minipage}{9cm}
+ \begin{center}
+ \includegraphics[height=8cm]{c_pd_vasp/110_2333_ksl.ps}
+ {\scriptsize \hkl<1 1 0> interstitial}
+ \end{center}
+ \end{minipage}
+
+\end{slide}
+
\begin{slide}
{\large\bf\boldmath
\begin{itemize}
\item Supercell: $3\times 3\times 3$ Type 2
\item Starting configuration: \hkl<0 0 -1> C-Si interstitial
+ ($E_{\text{f}}=3.15\text{ eV}$)
\item Energies: $E_{\text{f}}$ of the interstitial combinations in eV
\end{itemize}
\underline{Along \hkl<1 1 0>:}
- \begin{tabular}{|l|p{1.8cm}|p{1.8cm}|p{1.8cm}|p{1.8cm}|}
+ \begin{tabular}{|l|p{2.0cm}|p{1.8cm}|p{1.8cm}|p{1.8cm}|}
\hline
{\scriptsize
\backslashbox{2nd interstitial}{Distance $[\frac{a}{4}]$}
\hline
\hkl<-1 0 0>, \hkl<0 -1 0> & 3.92 & 4.43 & 6.02 & 6.02 \\
\hline
- Vacancy & ... & ... & ... & ... \\
+ Vacancy & 1.39 ($\rightarrow\text{ C}_{\text{S}}$)& 5.81 & 5.47 & 6.50 \\
\hline
\end{tabular}
\hline
& 2 & 3 & 4 & 5 & 6 \\
\hline
-\hkl<0 0 -1> & 6.23 & 5.16 & 6.23 & ... & 4.65\\
+\hkl<0 0 -1> & 6.23 & 5.16 & 6.23 & 6.35 & 4.65\\
\hline
-\hkl<0 0 1> & 6.64 & 6.31 & ... & ... & 4.78 \\
+\hkl<0 0 1> & 6.64 & 6.31 & 4.26 & 6.57 & 4.78 \\
\hline
-\hkl<1 0 0> & 4.06 & 6.13 & 6.21 & ... & 4.93 \\
+\hkl<1 0 0> & 4.06 & 6.13 & 6.21 & 6.03 & 4.93 \\
\hline
-\hkl<-1 0 0> & \hkl<0 -1 0> & 4.41 & ... & ... & 4.43 \\
+\hkl<-1 0 0> & \hkl<0 -1 0> & 4.41 & 4.06 & 6.19 & 4.43 \\
\hline
\hkl<0 1 0> & \hkl<1 0 0> & 5.95 & \hkl<-1 0 0> & \hkl<-1 0 0> & \hkl<1 0 0> \\
\hline
-\hkl<0 -1 0> & 3.92 & ... & \hkl<1 0 0> & \hkl<1 0 0> & \hkl <-1 0 0> \\
+\hkl<0 -1 0> & 3.92 & 4.15 & \hkl<1 0 0> & \hkl<1 0 0> & \hkl <-1 0 0> \\
\hline
-Vacancy & ... & ... & ... & ... & ... \\
+Vacancy & 1.39 & 6.19 & 3.65 & 6.24 & 6.50 \\
\hline
\end{tabular}
Reminder (just for me to keep in mind ...)
}
- \scriptsize
+ \small
\underline{Volume of the MD cell}
\begin{itemize}
- \item $T=900\text{ K}$
+ \item $T=450, 900, 1400\text{ K}$ - (no melting, N\underline{V}T!)
\item $\alpha=2.0 \cdot 10^{-6}\text{ K}^{-1}$
\item $a = a_0(1+\alpha \Delta T)$
\item Plain Si$(T=0)$: $a_0=5.4575\text{ \AA}$
\frac{1}{3}(a_0^x+a_0^y+a_0^z)=5.4605\text{ \AA}$
$\rightarrow a(900\text{ K})=5.4704{ \AA}$
\end{itemize}
- Used in the 900 K simulations: 5.4705 \AA\\
- Consider next thoughts as well!
+ Used in first 900 K simulations: 5.4705 \AA\\
+ BUT: Better use plain Si lattice constant! (only local distortions)\\
+ $\Rightarrow a(1400\text{ K})=5.4728\text{ \AA}$
\underline{Zero total momentum simulations}
\begin{itemize}
\item If C is randomly inserted there is a net total momentum
\item No correction in the temperature control routine of VASP?
- \item Relax a Si:C configuration first (at T=0)
+ \item Relax a Si:C configuration first
+ (at T=0, no volume relaxation, scaled volume)
\item Use this configuration as the MD initial configuration
\end{itemize}
- Two possibilities regarding volume which came to my mind:
- \begin{enumerate}
- \item Calculate and use an averaged $a_0$ (in each direction)
- from the relaxed configuration.
- Else there might be a preferred orientation for the defect.
- \item On the other hand this might be important
- for the way defects agglomerate.
- Continue using the relaxation results.
- \end{enumerate}
- In both methods the corrections due to the non zero temperature
- are applied!
\end{slide}