From a14f12a9addac7366d8065ac82188867df2c1d38 Mon Sep 17 00:00:00 2001 From: hackbard Date: Thu, 30 Jul 2009 17:28:41 +0200 Subject: [PATCH] new mig results --- posic/talks/upb-ua-xc.tex | 113 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 113 insertions(+) diff --git a/posic/talks/upb-ua-xc.tex b/posic/talks/upb-ua-xc.tex index 524ec2b..8561eb3 100644 --- a/posic/talks/upb-ua-xc.tex +++ b/posic/talks/upb-ua-xc.tex @@ -811,6 +811,7 @@ POTIM = 0.1 displaced by {\color{red}$\frac{1}{10}(\Delta x,\Delta y,\Delta z)$} \end{itemize} + \item Berendsen thermostat applied \end{itemize} {\bf\color{blue}Expected configuration not obtained!} \end{minipage} @@ -821,6 +822,118 @@ POTIM = 0.1 \includegraphics[width=6.0cm]{c_100_110mig_01_albe.ps} \end{minipage} +\end{slide} + +\begin{slide} + + {\large\bf + C 100 interstitial migration along 110 in c-Si (Albe potential) + } + + \footnotesize + + \begin{minipage}{3.2cm} + \includegraphics[width=3cm]{c_100_mig/fixmig_50.eps} + \begin{center} + 50 \% + \end{center} + \end{minipage} + \begin{minipage}{3.2cm} + \includegraphics[width=3cm]{c_100_mig/fixmig_80.eps} + \begin{center} + 80 \% + \end{center} + \end{minipage} + \begin{minipage}{3.2cm} + \includegraphics[width=3cm]{c_100_mig/fixmig_90.eps} + \begin{center} + 90 \% + \end{center} + \end{minipage} + \begin{minipage}{3.2cm} + \includegraphics[width=3cm]{c_100_mig/fixmig_99.eps} + \begin{center} + 100 \% + \end{center} + \end{minipage} + + Open questions ... + \begin{enumerate} + \item Why is the expected configuration not obtained? + \item How to find a migration path preceding to the expected configuration? + \end{enumerate} + + Answers ... + \begin{enumerate} + \item Simple: it is not the right migration path! + \begin{itemize} + \item (Surrounding) atoms settle into a local minimum configuration + \item A possibly existing more favorable configuration is not achieved + \end{itemize} + \item \begin{itemize} + \item Search global minimum in each step (by simulated annealing)\\ + {\color{red}But:} + Loss of the correct energy needed for migration + \item Smaller displacements\\ + A more favorable configuration might be achieved + possibly preceding to the expected configuration + \end{itemize} + \end{enumerate} + + +\end{slide} + +\begin{slide} + + {\large\bf + C 100 interstitial migration along 110 in c-Si (Albe potential)\\ + } + + Displacement step size decreased to + $\frac{1}{100} (\Delta x,\Delta y)$\\[0.2cm] + + \begin{minipage}{7.5cm} + Result: (Video \href{../video/c_in_si_smig_albe.avi}{$\rhd_{\text{local}}$ } $|$ + \href{http://www.physik.uni-augsburg.de/~zirkelfr/download/posic/c_in_si_smig_albe.avi}{$\rhd_{\text{remote url}}$}) + \begin{itemize} + \item Expected final configuration not obtained + \item Bonds to neighboured silicon atoms persist + \item C and neighboured Si atoms move along the direction of displacement + \item Even the bond to the lower left silicon atom persists + \end{itemize} + {\color{red} + Obviously: overestimated bond strength + } + \end{minipage} + \begin{minipage}{5cm} + \includegraphics[width=6cm]{c_100_110smig_01_albe.ps} + \end{minipage}\\[0.4cm] + New approach to find the migration path:\\ + {\color{blue} + Place interstitial carbon atom at the respective coordinates + into a perfect c-Si matrix! + } + +\end{slide} + +\begin{slide} + + {\large\bf + C 100 interstitial migration along 110 in c-Si (VASP) + } + + \small + \vspace*{1cm} + \ldots simulations running! + \vspace*{1cm} + + \begin{minipage}{5cm} + + \end{minipage} + \begin{minipage}{7cm} + + \end{minipage} + \end{slide} -- 2.39.2