X-Git-Url: https://hackdaworld.org/gitweb/?p=lectures%2Flatex.git;a=blobdiff_plain;f=posic%2Ftalks%2Fupb-ua-xc.tex;h=7b953ffafa28429c1e0274314340d37373e7db7d;hp=2a976157077480c5126e854b425b280687b2ec1d;hb=e08a97849ebaf34c088eef126bf83fa8a4267119;hpb=79e206cc88cb4dfb6e04eb6574474d550ee401e1 diff --git a/posic/talks/upb-ua-xc.tex b/posic/talks/upb-ua-xc.tex index 2a97615..7b953ff 100644 --- a/posic/talks/upb-ua-xc.tex +++ b/posic/talks/upb-ua-xc.tex @@ -20,6 +20,8 @@ \usepackage{pstricks} \usepackage{pst-node} +\usepackage{slashbox} + %\usepackage{epic} %\usepackage{eepic} @@ -1176,11 +1178,13 @@ POTIM = 0.1 } Needed so often for input configurations ...\\[0.8cm] - \begin{minipage}{7.7cm} - \includegraphics[width=7cm]{100-c-si-db_light.eps} - \hfill + \begin{minipage}{7.0cm} + \includegraphics[width=6.5cm]{100-c-si-db_light.eps}\\ + Qualitative {\color{red}and} quantitative {\color{red}difference}! \end{minipage} - \begin{minipage}{4.5cm} + \begin{minipage}{5.5cm} + \scriptsize + \begin{center} \begin{tabular}{|l|l|l|} \hline & a & b \\ @@ -1193,12 +1197,11 @@ POTIM = 0.1 fractional & 0.1547 & 0.1676 \\ in \AA & 0.84 & 0.91 \\ \hline - \end{tabular} - \end{minipage} - - \begin{center} - Qualitative {\color{red}and} quantitative {\color{red}difference}! + \end{tabular}\\[0.2cm] + {\scriptsize\underline{PC (Vasp)}} + \includegraphics[width=6.1cm]{c_100_pc_vasp.ps} \end{center} + \end{minipage} \end{slide} @@ -1208,7 +1211,8 @@ POTIM = 0.1 Again: C \hkl<1 0 0> interstitial migration (VASP) } - $\hkl<0 0 -1> \rightarrow \hkl<0 0 1>$ migration: + $\hkl<0 0 -1> \rightarrow \hkl<0 0 1>$ migration + ($3\times 3\times 3$ Type 2): \small @@ -1256,7 +1260,8 @@ POTIM = 0.1 Again: C \hkl<1 0 0> interstitial migration (VASP) } - $\hkl<0 0 -1> \rightarrow \hkl<0 -1 0>$ migration: + $\hkl<0 0 -1> \rightarrow \hkl<0 -1 0>$ migration + ($3\times 3\times 3$ Type 2): \small @@ -1285,41 +1290,1657 @@ POTIM = 0.1 \Rightarrow \Delta E_{\text{f}} = E_{\text{mig}} = ?.?? \text{ eV} \] - Unexpected \& ({\color{red}more} or {\color{orange}less}) fatal: + \vspace*{0.5cm} + {\large\bf + Intermediate configuration {\color{red}not found} by now! + } + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + C in Si interstitial configurations (VASP) + } + + Check of Kohn-Sham eigenvalues\\ + + \small + + \begin{minipage}{6cm} + \hkl<1 0 0> interstitial\\ + \end{minipage} + \begin{minipage}{6cm} + Saddle point configuration\\ + \end{minipage} + \underline{$4\times 4\times 3$ Type 1 - fixed border atoms}\\ + \begin{minipage}{6cm} +385: 4.8567 - 2.00000\\ +386: 4.9510 - 2.00000\\ +387: 5.3437 - 0.00000\\ +388: 5.4930 - 0.00000 + \end{minipage} + \begin{minipage}{6cm} +385: 4.8694 - 2.00000\\ +386: {\color{red}4.9917} - 1.92603\\ +387: {\color{red}5.1181} - 0.07397\\ +388: 5.4541 - 0.00000 + \end{minipage}\\[0.2cm] + \underline{$4\times 4\times 3$ Type 1 - no constraints}\\ + \begin{minipage}{6cm} +385: 4.8586 - 2.00000\\ +386: 4.9458 - 2.00000\\ +387: 5.3358 - 0.00000\\ +388: 5.4915 - 0.00000 + \end{minipage} + \begin{minipage}{6cm} +385: 4.8693 - 2.00000\\ +386: {\color{red}4.9879} - 1.92065\\ +387: {\color{red}5.1120} - 0.07935\\ +388: 5.4544 - 0.00000 + \end{minipage}\\[0.2cm] + \underline{$3\times 3\times 3$ Type 2 - no constraints}\\ + \begin{minipage}{6cm} +433: 4.8054 - 2.00000\\ +434: 4.9027 - 2.00000\\ +435: 5.2543 - 0.00000\\ +436: 5.5718 - 0.00000 + \end{minipage} + \begin{minipage}{6cm} +433: 4.8160 - 2.00000\\ +434: {\color{green}5.0109} - 1.00264\\ +435: {\color{green}5.0111} - 0.99736\\ +436: 5.5364 - 0.00000 + \end{minipage} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Once again: C \hkl<1 0 0> interstitial migration (VASP) + } + + Method: \begin{itemize} - \renewcommand\labelitemi{{\color{orange}$\bullet$}} - \item Difference in formation energy (0.02 eV) - of the initial and final configuration - \renewcommand\labelitemi{{\color{red}$\bullet$}} - \item Huge discrepancy (0.3 - 0.4 eV) to the migration barrier - of Type 1 (198+1 atoms) calculations - \renewcommand\labelitemi{{\color{black}$\bullet$}} + \item Start in fully relaxed (assumed) saddle point configuration + \item Move towards \hkl<1 0 0> configuration using updated values + for $\Delta x$, $\Delta y$ and $\Delta z$ (CRT) + \item \hkl<1 1 0> constraints applied, 1 Si atom fixed + \item $4\times 4\times 3$ Type 1 supercell \end{itemize} - + + Results: + + \begin{minipage}{6.2cm} + \includegraphics[width=6.0cm]{c_100_110sp-i_vasp.ps} + \end{minipage} + \begin{minipage}{6.2cm} + \includegraphics[width=6.0cm]{c_100_110sp-i_rc_vasp.ps} + \end{minipage} + + Reaction coordinate: + $r_{i+1}=r_i+\sum_{\text{atoms j}} \left| r_{j,i+1}-r_{j,i} \right|$ + \end{slide} \begin{slide} - {\large\bf - Molecular dynamics simulations (VASP) + {\large\bf\boldmath + Investigation of the migration path along \hkl<1 1 0> (VASP) } \small + \underline{Minimum:}\\ + \begin{minipage}{4cm} + \includegraphics[width=3.5cm]{c_100_mig_vasp/110_c-si_split.eps} + \end{minipage} + \begin{minipage}{8cm} + \begin{itemize} + \item Starting conf: 35 \% displacement results (1443) + \item \hkl<1 1 0> constraint disabled + \end{itemize} + \begin{center} + $\Downarrow$ + \end{center} + \begin{itemize} + \item C-Si \hkl<1 1 0> split interstitial + \item Stable configuration + \item $E_{\text{f}}=4.13\text{ eV}$ + \end{itemize} + \end{minipage}\\[0.1cm] + + \underline{Maximum:}\\ + \begin{minipage}{6cm} + \begin{center} + \includegraphics[width=2.3cm]{c_100_mig_vasp/100-110_01.eps} + \includegraphics[width=2.3cm]{c_100_mig_vasp/100-110_02.eps}\\ + 20 \% $\rightarrow$ 25 \%\\ + Breaking of Si-C bond + \end{center} + \end{minipage} + \begin{minipage}{6cm} + \includegraphics[width=6.2cm]{c_100_110sp-i_upd_vasp.ps} + \end{minipage} + \end{slide} \begin{slide} - {\large\bf - Density Functional Theory + {\large\bf\boldmath + Displacing the \hkl<1 1 0> Si-C split along \hkl<1 -1 0> (VASP) } - Hohenberg-Kohn theorem + \small + + $4\times 4\times 3$ Type 1 supercell + + \underline{Structures:} + + \begin{minipage}[t]{4.1cm} + \includegraphics[height=3.0cm]{c_100_mig_vasp/start.eps}\\ + \hkl<0 0 -1> dumbbell\\ + $E_{\text{f}}={\color{orange}3.2254}\text{ eV}$ + \end{minipage} + \begin{minipage}[t]{4.1cm} + \includegraphics[height=3.0cm]{c_100_mig_vasp/110_c-si_split.eps}\\ + Assumed \hkl<1 1 0> C-Si split\\ + $E_{\text{f}}=4.1314\text{ eV}$ + \end{minipage} + \begin{minipage}[t]{4.1cm} + \includegraphics[height=3.0cm]{c_100_mig_vasp/110_dis_0-10.eps}\\ + First guess: \hkl<0 -1 0> dumbbell\\ + {\color{red}but:} $E_{\text{f}}={\color{orange}2.8924}\text{ eV}$\\ + Third bond missing! + \end{minipage}\\ + + \underline{Occupancies:} + + \scriptsize + + \begin{minipage}{4.1cm} +385: 4.8586 - 2.00000\\ +386: 4.9458 - 2.00000\\ +387: 5.3358 - 0.00000\\ +388: 5.4915 - 0.00000 +\hfill + \end{minipage} + \begin{minipage}{4.1cm} +385: 4.7790 - 2.00000\\ +386: 4.8797 - 1.99964\\ +387: 5.1321 - 0.00036\\ +388: 5.4711 - 0.00000 +\hfill + \end{minipage} + \begin{minipage}{4.1cm} +385: 4.7670 - 2.00000\\ +386: 4.9190 - 2.00000\\ +387: 5.2886 - 0.00000\\ +388: 5.4849 - 0.00000 +\hfill + \end{minipage}\\ + +\small + + \begin{center} + {\color{red}? ! ? ! ? ! ? ! ?} + \end{center} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + C \hkl<1 0 0> interstitial migration (VASP) + } \small + + \begin{minipage}{6.2cm} + \begin{itemize} + \item $3\times 3\times 3$ Type 2 supercell + \item \hkl<1 1 0> constraints applied + (\href{http://www.physik.uni-augsburg.de/~zirkelfr/download/posic/sd_rot.patch}{Patch}) + \item Move from \hkl<1 0 0> towards\\ + bond centered configuration + \end{itemize} + \underline{Sd Rot usage (POSCAR):} +\begin{verbatim} +cubic diamond +5.480 + 3.0 0.0 0.0 + 0.0 3.0 0.0 + 0.0 0.0 3.0 +216 1 +Transformed selective dynamics +45.0 0.0 +Direct + ... +\end{verbatim} +Only works in direct mode!\\ +$z,x'$-axis rotation: $45.0^{\circ}$, $0.0^{\circ}$ + \end{minipage} + \begin{minipage}{6.2cm} + \includegraphics[width=5cm]{c_100_110sp-i_2333_vasp.ps} + \includegraphics[width=5cm]{c_100_110sp-i_2333_rc_vasp.ps}\\ + {\color{red}One fixed Si atom not enough!}\\ + Video: \href{../video/c_in_si_233_110mig_vasp.avi}{$\rhd_{\text{local}}$ } $|$ + \href{http://www.physik.uni-augsburg.de/~zirkelfr/download/posic/c_in_si_233_110mig_vasp.avi}{$\rhd_{\text{remote url}}$}\\ + \end{minipage} + + {\color{blue} + Next: Migration calculation in 2333 using CRT + (\hkl<0 0 -1> $\rightarrow$ \hkl<0 0 1> and \hkl<0 -1 0>) + } + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Defect configurations in $4\times 4\times 3$ Type 1 supercells revisited + } + + \footnotesize + + \begin{tabular}{l|p{2.5cm}|p{2.5cm}|p{4cm}|} + & \hkl<0 0 -1> interstitial + & local minimum\newline + \hkl<1 1 0> C-Si split + & intermediate configuration\newline + (bond centered conf)\\ + \hline + default & $E_{\text{f}}=3.3254\text{ eV}$\newline + {\tiny + 386: 4.9458 - 2.00000\newline + 387: 5.3358 - 0.00000} + & $E_{\text{f}}=4.1314\text{ eV}$\newline + {\tiny + 386: 4.8797 - 1.99964\newline + 387: 5.1321 - 0.00036} + & $E_{\text{f}}=4.2434\text{ eV}$\newline + {\tiny + 386: 4.9879 - 1.92065\newline + 387: 5.1120 - 0.07935} \\ + \hline + No symmetry & $E_{\text{f}}=3.3154\text{ eV}$\newline + {\tiny + 386: 4.9456 - 2.00000\newline + 387: 5.3366 - 0.00000} + & $E_{\text{f}}=4.1314\text{ eV}$\newline + {\tiny + 386: 4.8798 - 1.99961\newline + 387: 5.1307 - 0.00039} + & $E_{\text{f}}=4.2454\text{ eV}$\newline + {\tiny + 386: 4.9841 - 1.92147\newline + 387: 5.1085 - 0.07853} \\ + \hline + $+$ spin polarized & $E_{\text{f}}=3.3154\text{ eV}$\newline + {\tiny + {\color{blue} + 386: 4.9449 - 1.00000\newline + 387: 5.3365 - 0.00000\newline% + }% + {\color{green}% + 386: 4.9449 - 1.00000\newline + 387: 5.3365 - 0.00000}} + & $E_{\text{f}}={\color{red}4.1314}\text{ eV}$\newline + {\tiny + {\color{blue} + 386: 4.8799 - 0.99980\newline + 387: 5.1307 - 0.00020\newline% + }% + {\color{green}% + 386: 4.8799 - 0.99980\newline + 387: 5.1306 - 0.00020}} + & $E_{\text{f}}=4.0254\text{ eV}$\newline + {\tiny + {\color{blue} + 387: 4.8581 - 1.00000\newline + 388: 5.4662 - 0.00000\newline% + }% + {\color{green}% + 385: 4.8620 - 1.00000\newline + 386: 5.2951 - 0.00000}} \\ + \hline + $+$ spin difference 2 & $E_{\text{f}}=3.6394\text{ eV}$\newline + {\tiny + {\color{blue} + 387: 5.2704 - 0.99891\newline + 388: 5.4886 - 0.00095\newline + 389: 5.5094 - 0.00011\newline + 390: 5.5206 - 0.00003\newline% + }% + {\color{green}% + 385: 4.8565 - 0.98603\newline + 386: 5.0119 - 0.01397}} + & Relaxation into\newline + bond centered\newline + configuration\newline + $\rightarrow$ + & $E_{\text{f}}=4.0254\text{ eV}$\newline + {\tiny + {\color{blue} + 387: 4.8578 - 1.00000\newline + 388: 5.4661 - 0.00000\newline% + }% + {\color{green}% + 385: 4.8618 - 1.00000\newline + 386: 5.2950 - 0.00000}} \\ + \hline + \end{tabular} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Defect configurations in $3\times 3\times 3$ Type 2 supercells revisited\\ + } + + \footnotesize + + \begin{tabular}{l|p{2.5cm}|p{2.5cm}|p{4cm}|} + & \hkl<0 0 -1> interstitial + & local minimum\newline + \hkl<1 1 0> C-Si split + & intermediate configuration\newline + (bond centered conf)\\ + \hline + default & $E_{\text{f}}=3.15407\text{ eV}$\newline + {\tiny + 434: 4.9027 - 2.00000\newline + 435: 5.2543 - 0.00000} + & $E_{\text{f}}=??\text{ eV}$\newline + {\tiny + ??\newline + ??} + & $E_{\text{f}}=4.40907\text{ eV}$\newline + {\tiny + 434: 5.0109 - 1.00264\newline + 435: 5.0111 - 0.99736}\\ + \hline + No symmetry & $E_{\text{f}}=3.16107\text{ eV}$\newline + {\tiny + 434: 4.9032 - 2.00000\newline + 435: 5.2547 - 0.00000} + & $E_{\text{f}}=??\text{ eV}$\newline + {\tiny + ??\newline + ??} + & $E_{\text{f}}=4.41507\text{ eV}$\newline + {\tiny + 434: 5.0113 - 1.00140\newline + 435: 5.0114 - 0.99860} \\ + \hline + $+$ spin polarized & $E_{\text{f}}=3.16107\text{ eV}$\newline + {\tiny + {\color{blue} + 434: 4.9033 - 1.00000\newline + 435: 5.2544 - 0.00000\newline% + }% + {\color{green}% + 434: 4.9035 - 1.00000\newline + 435: 5.2550 - 0.00000}} + & $E_{\text{f}}=??\text{ eV}$\newline + {\tiny + {\color{blue} + ??\newline + ??\newline% + }% + {\color{green}% + ??\newline + ??}} + & $E_{\text{f}}=4.10307\text{ eV}$\newline + {\tiny + {\color{blue} + 435: 4.8118 - 1.00000\newline + 436: 5.5360 - 0.00000\newline% + }% + {\color{green}% + 433: 4.8151 - 1.00000\newline + 434: 5.3475 - 0.00000}} \\ + \hline + \end{tabular} + + \normalsize + + \vspace*{0.3cm} + + {\color{blue}Tracer:}\\ + Smearing of electrons over two or more (degenerated) energy levels\\ + $\Rightarrow$ use spin polarized calculations! + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Bond centered configuration revisited ($3\times 3\times 3$ Type 2) + } + + Spin polarized calculations + + {\small + \begin{minipage}[t]{5.8cm} + \underline{Kohn-Sham eigenvalues}\\ + \begin{minipage}{2.8cm} + Spin up:\\ + 430: 4.2639 - 1\newline + 431: 4.7332 - 1\newline + 432: 4.7354 - 1\newline + 433: 4.7700 - 1\newline + 434: 4.8116 - 1\newline + 435: 4.8118 - 1\newline + 436: 5.5360 - 0\newline + 437: 5.5623 - 0 + \end{minipage} + \begin{minipage}{2.8cm} + Spin down:\\ + 430: 4.2682 - 1\newline + 431: 4.7738 - 1\newline + 432: 4.8150 - 1\newline + 433: 4.8151 - 1\newline + 434: 5.3475 - 0\newline + 435: 5.3476 - 0\newline + 436: 5.5455 - 0\newline + 437: 5.5652 - 0 + \end{minipage}\\[0.3cm] + \begin{itemize} + \item linear Si-C-Si bond + \item Each Si has another 3 Si neighbours + \end{itemize} + \begin{center} + {\color{blue}Spin polarized calculations necessary!}\\[0.3cm] + \end{center} + {\scriptsize Charge density isosurface of + {\color{gray}spin up}, {\color{green}spin down} and + the {\color{blue}resulting spin up} electrons.\\ + Two {\color{yellow} Si} atoms and one {\color{red}C} + atom are shown. + } + \end{minipage} + \begin{minipage}[t]{6.5cm} + \underline{MO diagram}\\ + \begin{minipage}[t]{1.2cm} + {\color{red}Si}\\ + {\tiny sp$^3$}\\[0.8cm] + \underline{${\color{red}\uparrow}$} + \underline{${\color{red}\uparrow}$} + \underline{${\color{red}\uparrow}$} + \underline{${\color{red}\uparrow}$}\\ + sp$^3$ + \end{minipage} + \begin{minipage}[t]{1.4cm} + \begin{center} + {\color{red}M}{\color{blue}O}\\[1.0cm] + \underline{${\color{blue}\uparrow}{\color{white}\downarrow}$}\\ + $\sigma_{\text{ab}}$\\[0.5cm] + \underline{${\color{red}\uparrow}{\color{blue}\downarrow}$}\\ + $\sigma_{\text{b}}$ + \end{center} + \end{minipage} + \begin{minipage}[t]{1.0cm} + \begin{center} + {\color{blue}C}\\ + {\tiny sp}\\[0.2cm] + \underline{${\color{white}\uparrow\uparrow}$} + \underline{${\color{white}\uparrow\uparrow}$}\\ + 2p\\[0.4cm] + \underline{${\color{blue}\uparrow}{\color{blue}\downarrow}$} + \underline{${\color{blue}\uparrow}{\color{blue}\downarrow}$}\\ + sp + \end{center} + \end{minipage} + \begin{minipage}[t]{1.4cm} + \begin{center} + {\color{blue}M}{\color{green}O}\\[1.0cm] + \underline{${\color{blue}\uparrow}{\color{white}\downarrow}$}\\ + $\sigma_{\text{ab}}$\\[0.5cm] + \underline{${\color{green}\uparrow}{\color{blue}\downarrow}$}\\ + $\sigma_{\text{b}}$ + \end{center} + \end{minipage} + \begin{minipage}[t]{1.2cm} + \begin{flushright} + {\color{green}Si}\\ + {\tiny sp$^3$}\\[0.8cm] + \underline{${\color{green}\uparrow}$} + \underline{${\color{green}\uparrow}$} + \underline{${\color{green}\uparrow}$} + \underline{${\color{green}\uparrow}$}\\ + sp$^3$ + \end{flushright} + \end{minipage}\\[0.4cm] + \begin{flushright} + \includegraphics[width=6cm]{c_100_mig_vasp/im_spin_diff.eps} + \end{flushright} + \end{minipage} + } + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + \hkl<0 0 -1> configuration revisited ($3\times 3\times 3$ Type 2) + } + + Spin polarized calculations + + {\small + \begin{minipage}[t]{5.8cm} + \underline{Kohn-Sham eigenvalues}\\ + \begin{minipage}{2.8cm} + Spin up:\\ + 430: 4.3317 - 1\newline + 431: 4.7418 - 1\newline + 432: 4.8014 - 1\newline + 433: 4.8060 - 1\newline + 434: 4.9033 - 1\newline + 435: 5.2544 - 0\newline + 436: 5.5723 - 0\newline + 437: 5.5848 - 0 + \end{minipage} + \begin{minipage}{2.8cm} + Spin down:\\ + 430: 4.3317 - 1\newline + 431: 4.7420 - 1\newline + 432: 4.8013 - 1\newline + 433: 4.8059 - 1\newline + 434: 4.9035 - 1\newline + 435: 5.2550 - 0\newline + 436: 5.5724 - 0\newline + 437: 5.5846 - 0 + \end{minipage} + \end{minipage} + \begin{minipage}[t]{6.5cm} + \underline{MO diagram}\\ + \begin{minipage}[t]{1.2cm} + {\color{red}Si}\\ + {\tiny sp$^2$}\\[0.1cm] + \underline{${\color{white}\uparrow}$}\\ + p\\[0.4cm] + \underline{${\color{red}\uparrow\downarrow}$} + \underline{${\color{red}\uparrow}{\color{white}\downarrow}$} + \underline{${\color{red}\uparrow}{\color{white}\downarrow}$}\\ + sp$^2$ + \end{minipage} + \begin{minipage}[t]{1.2cm} + \begin{flushright} + {\color{red}M}\\[1.0cm] + \underline{${\color{white}\uparrow}{\color{white}\downarrow}$}\\ + $\sigma_{\text{ab}}$\\[0.5cm] + \underline{${\color{red}\uparrow}{\color{blue}\downarrow}$}\\ + $\sigma_{\text{b}}$ + \end{flushright} + \end{minipage} + \begin{minipage}[t]{1.2cm} + \begin{flushleft} + {\color{blue}O}\\[0.4cm] + \underline{${\color{white}\uparrow}{\color{white}\downarrow}$}\\ + $\pi_{\text{ab}}$\\[0.5cm] + \underline{${\color{red}\uparrow}{\color{blue}\downarrow}$}\\ + $\pi_{\text{b}}$ + \end{flushleft} + \end{minipage} + \begin{minipage}[t]{2.0cm} + \begin{center} + {\color{blue}C}\\ + {\tiny sp$^2$}\\[0.5cm] + \underline{${\color{white}\uparrow\uparrow}$}\\ + p\\[0.4cm] + \underline{${\color{blue}\uparrow}{\color{blue}\downarrow}$} + \underline{${\color{blue}\uparrow}{\color{white}\downarrow}$} + \underline{${\color{blue}\uparrow}{\color{white}\downarrow}$}\\ + sp$^2$ + \end{center} + \end{minipage} + \end{minipage} + } + + \vspace*{0.4cm} + + \begin{itemize} + \item Si-C double bond + \item Si and C atom have another 2 Si neighbours + \end{itemize} + \begin{center} + {\color{blue}Spin polarized calculations {\color{red}not} necessary!} + \end{center} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Kohn-Sham levels visualized + } + + \begin{minipage}{6cm} + \underline{\hkl<0 0 -1> configuration} + \begin{center} + \includegraphics[height=8cm]{c_100_mig_vasp/100_ksl.ps} + \end{center} + \end{minipage} + \begin{minipage}{6cm} + \underline{Saddle point configuration} + \begin{center} + \includegraphics[height=8cm]{c_100_mig_vasp/im_ksl.ps} + \end{center} + \end{minipage} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Saddle point configuration check + } + + Simulations: + \begin{itemize} + \item Displacing the C atom in the BC configuration + \begin{itemize} + \item in \hkl<1 -1 0> direction\\ + $(0.1240, 0.1240, 0.0409) \rightarrow + (0.1340, 0.1140, 0.0409)$ + \item in \hkl<1 0 0> direction\\ + $(0.1240, 0.1240, 0.0409) \rightarrow + (0.1440, 0.1240, 0.0409)$ + \end{itemize} + \item Full relaxation of the configuration + \end{itemize} + + Results: + \begin{itemize} + \item Both displacement simulations relax to + the BC configuration + \item Obviously the second derivative with respect to the + migration direction is also positive + \end{itemize} + + \begin{center} + $\Downarrow$\\ + Bond centered configuration is a + {\color{blue}real local minimum} + and {\color{red}not} a saddle point configuration + \end{center} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + New default parameter set\\[1cm] + } + + Since some defect configurations need spin polarized calculations ...\\[1cm] + + from now on the default parameter set\\ + {\bf\color{blue} + $+$ no symmetry\\ + $+$ spin polarized\\ + } + \ldots is used!\\[1cm] + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + BC to \hkl<0 0 -1> migration + in the $3\times 3\times 3$ Type 2 supercell + } + + \begin{minipage}{6cm} + Method: + \begin{itemize} + \item Starting configuration:\\ + C bond centered + \item CRT towards \hkl<0 0 -1> configuration + \item Spin polarized calculations + \end{itemize} + Results:\\ + Video \href{../video/c_im_00-1_vasp.avi}{$\rhd_{\text{local}}$ } $|$ + \href{http://www.physik.uni-augsburg.de/~zirkelfr/download/posic/c_im_00-1_vasp.avi}{$\rhd_{\text{remote url}}$} + \begin{itemize} + \item Still abrupt changes in configuration and energy + \item Migration barrier $>$ 1 eV + \end{itemize} + \end{minipage} + \begin{minipage}{6cm} + \includegraphics[width=6cm]{c_im_001_mig_vasp.ps} + \includegraphics[width=6cm]{c_im_001_mig_rc_vasp.ps} + \end{minipage} \end{slide} +\begin{slide} + + {\large\bf\boldmath + \hkl<0 0 -1> to \hkl<0 -1 0> migration + in the $3\times 3\times 3$ Type 2 supercell + } + + \includegraphics[width=6cm]{c_00-1_0-10_mig_vasp.ps} + \includegraphics[width=6cm]{c_00-1_0-10_mig_dis_vasp.ps} + + Calculations without spin:\\ + Video \href{../video/c_00-1_0-10_vasp.avi}{$\rhd_{\text{local}}$ } $|$ + \href{http://www.physik.uni-augsburg.de/~zirkelfr/download/posic/c_00-1_0-10_vasp.avi}{$\rhd_{\text{remote url}}$} ... WAAAAH!!! + \begin{itemize} + \item Refined starting from 70\% due to + abrubt jumps in energy and configuration + \item Displacement from 80 to 85\% disastrous + \item Subsequent displacements too large + \end{itemize} + + Waiting for spin polarized calculations before deciding what to do ... + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + C \hkl<1 0 0> migration - yet another method! + } + + {\color{red}Problem:} + + Abrubt changes in atomic configurations (and energy) + in consecutive steps. + In addition - sometimes - the final configuration is not obtained! + + {\color{blue}New method:} + + Displace {\color{red}all} atoms towards the final configuration + and apply corresponding constraints for each atom. + + Usage: + (\href{http://www.physik.uni-augsburg.de/~zirkelfr/download/posic/sd_rot_all-atoms.patch}{Patch}) + +\footnotesize + +\begin{verbatim} +cubic diamond + 5.48000000000000 + 2.9909698580839312 0.0039546630279804 -0.0039658085666586 + 0.0039548953566878 2.9909698596656376 -0.0039660323646892 + -0.0039680658132861 -0.0039674231313905 2.9909994291263242 + 216 1 +Transformed selective dynamics +Direct + 0.994174 0.994174 -0.000408732 T F T 45 36.5145 + 0.182792 0.182792 0.981597 T F T -135 -5.95043 + ... + 0.119896 0.119896 0.0385525 T F T -135 21.8036 +\end{verbatim} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + BC to \hkl<0 0 -1> migration (all atoms CRT) + } + + \includegraphics[width=6cm]{im_00-1_nosym_sp_fullct.ps} + \includegraphics[width=6cm]{im_00-1_nosym_sp_fullct_rc.ps} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + \hkl<0 0 -1> to \hkl<0 -1 0> migration (all atoms CRT) + } + + \includegraphics[width=6cm]{00-1_0-10_nosym_sp_fullct.ps} + \includegraphics[width=6cm]{00-1_0-10_nosym_sp_fullct_rc.ps} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + \hkl<0 0 -1> to \hkl<0 -1 0> migration in place (all atoms CRT) + } + + \includegraphics[width=6cm]{00-1_ip0-10_nosym_sp_fullct.ps} + \includegraphics[width=6cm]{00-1_ip0-10_nosym_sp_fullct_rc.ps} + + in progress ... + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Combination of defects + } + + TODO: introduce some Si self-interstitials and C interstitials before\\ + BUT: Concentrate on 100 C interstitial combinations and 100 C + vacancy\\ + + Agglomeration of 100 defects energetically favorable? + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Silicon point defects + } + + \begin{minipage}{3.2cm} + \underline{Vacancy} + \begin{itemize} + \item $E_{\text{f}}=3.63\text{ eV}$ + \end{itemize} + \includegraphics[width=3cm]{si_pd_vasp/vac_2333.eps}\\ + \underline{\hkl<1 1 0> interstitial} + \begin{itemize} + \item $E_{\text{f}}=3.39\text{ eV}$ + \end{itemize} + \includegraphics[width=3cm]{si_pd_vasp/110_2333.eps} + \end{minipage} + \begin{minipage}{4.5cm} + \begin{center} + \includegraphics[height=8cm]{si_pd_vasp/vac_2333_ksl.ps}\\ + {\scriptsize Vacancy} + \end{center} + \end{minipage} + \begin{minipage}{4.5cm} + \begin{center} + \includegraphics[height=8cm]{si_pd_vasp/110_2333_ksl.ps} + {\scriptsize \hkl<1 1 0> interstitial} + \end{center} + \end{minipage} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Silicon point defects + } + + \begin{minipage}{3.1cm} + \underline{Hexagonal} + \begin{itemize} + \item $E_{\text{f}}=3.42\text{ eV}$ + \end{itemize} + \includegraphics[width=3cm]{si_pd_vasp/hex_2333.eps}\\ + \underline{Tetrahedral} + \begin{itemize} + \item $E_{\text{f}}=3.77\text{ eV}$ + \end{itemize} + \includegraphics[width=3cm]{si_pd_vasp/tet_2333.eps} + \end{minipage} + \begin{minipage}{3.7cm} + \begin{center} + \includegraphics[height=8cm]{si_pd_vasp/hex_2333_ksl.ps}\\ + {\scriptsize Hexagonal} + \end{center} + \end{minipage} + \begin{minipage}{3.7cm} + \begin{center} + \includegraphics[height=8cm]{si_pd_vasp/tet_2333_ksl.ps} + {\scriptsize Tetrahedral} + \end{center} + \end{minipage} + \begin{minipage}[c]{0.1cm} + \hfill + \end{minipage} + \begin{minipage}[c]{1.9cm} +{\tiny +\underline{Energy - Occup.}\\ +5.5063 - 0.32840\\ +5.5064 - 0.32793\\ +5.5064 - 0.32764\\ +5.5777 - 0.00691\\ +5.5777 - 0.00691\\ +5.6031 - 0.00074\\ +5.6031 - 0.00074\\ +5.6035 - 0.00071\\ +5.6357 - 0.00002\\ +5.6453 - 0.00001\\ +5.6453 - 0.00001 +} + \end{minipage} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Silicon point defects + } + + \begin{minipage}{3.1cm} + \underline{\hkl<1 0 0> interstitial} + \begin{itemize} + \item $E_{\text{f}}=4.41\text{ eV}$ + \end{itemize} + \includegraphics[width=3cm]{si_pd_vasp/100_2333.eps}\\ + \end{minipage} + \begin{minipage}{3.7cm} + \begin{center} + \includegraphics[height=8cm]{si_pd_vasp/100_2333_ksl.ps}\\ + {\scriptsize \hkl<1 0 0> interstitial} + \end{center} + \end{minipage} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Carbon point defects in silicon + } + + \begin{minipage}{3.2cm} + \underline{C substitutional} + \begin{itemize} + \item $E_{\text{f}}=1.39\text{ eV}$ + \end{itemize} + \includegraphics[width=3cm]{c_pd_vasp/sub_2333.eps}\\ + \underline{\hkl<1 0 0> interstitial} + \begin{itemize} + \item $E_{\text{f}}=3.15\text{ eV}$ + \end{itemize} + \includegraphics[width=3cm]{c_pd_vasp/100_2333.eps} + \end{minipage} + \begin{minipage}{4.5cm} + \begin{center} + \includegraphics[height=8cm]{c_pd_vasp/sub_2333_ksl.ps}\\ + {\scriptsize C substitutional} + \end{center} + \end{minipage} + \begin{minipage}{4.5cm} + \begin{center} + \includegraphics[height=8cm]{c_pd_vasp/100_2333_ksl.ps} + {\scriptsize \hkl<1 0 0> interstitial} + \end{center} + \end{minipage} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Carbon point defects in silicon + } + + \begin{minipage}{3.2cm} + \underline{C bond centered} + \begin{itemize} + \item $E_{\text{f}}=4.10\text{ eV}$ + \end{itemize} + \includegraphics[width=3cm]{c_pd_vasp/bc_2333.eps} + \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}{4.5cm} + \begin{center} + \includegraphics[height=8cm]{c_pd_vasp/110_2333_ksl.ps} + {\scriptsize \hkl<1 1 0> interstitial} + \end{center} + \end{minipage} + \begin{minipage}{4.5cm} + \begin{center} + \includegraphics[height=8cm]{c_pd_vasp/bc_2333_ksl.ps} + {\scriptsize C bond centered} + \end{center} + \end{minipage} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Carbon point defects in silicon + } + + The hexagonal and tetrahedral C configurations both relax into the + \hkl<0 0 1> interstitial configuration! + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Combination of defects + } + + \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{2.0cm}|p{1.8cm}|p{1.8cm}|p{1.8cm}|} + \hline + {\scriptsize + \backslashbox{2nd interstitial}{Distance $[\frac{a}{4}]$} + } + & \hkl<1 1 -1> & \hkl<2 2 0> & \hkl<3 3 -1> & \hkl<4 4 0>\\ + \hline + \hkl<0 0 -1> & 6.23\newline {\color{blue}6.23514} + & 4.65\newline {\color{blue}4.65014} + & 5.97\newline {\color{blue}5.97314} + & 6.45\newline {\color{blue}6.45714} \\ + \hline + \hkl<0 0 1> & 6.64\newline {\color{blue}6.65114} + & 4.78\newline {\color{blue}4.78314} + & 6.53\newline {\color{blue}6.53614} + & 6.18\newline {\color{blue}6.18914} \\ + \hline + \hkl<1 0 0>, \hkl<0 1 0> & 4.06\newline alkmene + & 4.93 + & 5.72 + & 6.00\\ + \hline + \hkl<-1 0 0>, \hkl<0 -1 0> & 3.92 & 4.43 & 6.02 & 6.02 \\ + \hline + Vacancy & 1.39 ($\rightarrow\text{ C}_{\text{S}}$)& 5.81 & 5.47 & 6.50 \\ + \hline + \end{tabular} + + Spin polarized and {\color{blue}non spin polarized} results + +\end{slide} + +\begin{slide} + + \begin{minipage}{5cm} + {\large\bf\boldmath + Combination of defects + } + + \scriptsize + + Initial insterstital at: $\frac{1}{4}\hkl<1 1 1>$ + + Relative silicon neighbour positions: + \begin{enumerate} + \item The dumbbell Si + \item $\frac{1}{4}\hkl<1 1 -1>$, $\frac{1}{4}\hkl<-1 -1 -1>$ + \item $\frac{1}{2}\hkl<1 0 -1>$, $\frac{1}{2}\hkl<0 1 -1>$, + $\frac{1}{2}\hkl<0 -1 -1>$, $\frac{1}{2}\hkl<-1 0 -1>$ + \item $\frac{1}{4}\hkl<1 -1 1>$, $\frac{1}{4}\hkl<-1 1 1>$ + \item $\frac{1}{4}\hkl<-1 1 -3>$, $\frac{1}{4}\hkl<1 -1 -3>$ + \item $\frac{1}{2}\hkl<-1 -1 0>$, $\frac{1}{2}\hkl<1 1 0>$ + \item $\frac{1}{2}\hkl<1 -1 0>$, $\frac{1}{2}\hkl<-1 1 0>$ + \item $\frac{1}{4}\hkl<-1 3 -1>$, $\frac{1}{4}\hkl<1 -3 -1>$, + $\frac{1}{4}\hkl<3 -1 -1>$. $\frac{1}{4}\hkl<-3 1 -1>$ + \item $\hkl<0 0 -1>$ + \item $\frac{1}{2}\hkl<1 0 1>$, $\frac{1}{2}\hkl<0 1 1>$, + $\frac{1}{2}\hkl<0 -1 1>$, $\frac{1}{2}\hkl<-1 0 1>$ + \item $\frac{1}{4}\hkl<-1 -3 1>$, $\frac{1}{4}\hkl<-3 -1 1>$, + $\frac{1}{4}\hkl<1 3 1>$, $\frac{1}{4}\hkl<3 1 1>$ + \item $\frac{1}{4}\hkl<1 3 -3>$, $\frac{1}{4}\hkl<3 1 -3>$, + $\frac{1}{4}\hkl<-1 -3 -3>$, $\frac{1}{4}\hkl<-3 -1 -3>$ + \item $\hkl<1 0 0>$, $\hkl<0 1 0>$, $\hkl<-1 0 0>$, $\hkl<0 -1 0>$ + \item $\frac{1}{4}\hkl<1 1 3>$, $\frac{1}{4}\hkl<-1 -1 3>$ + \item $\frac{1}{4}\hkl<3 3 -1>$, $\frac{1}{4}\hkl<-3 -3 -1>$ + \item $\frac{1}{2}\hkl<1 1 -2>$, $\frac{1}{2}\hkl<-1 -1 -2>$, + \item $\frac{1}{2}\hkl<1 -1 -2>$, $\frac{1}{2}\hkl<-1 1 -2>$ + \end{enumerate} + One of a kind\\ + {\color{red}Two of a kind}\\ + {\color{blue}Four of a kind} + \end{minipage} + \begin{minipage}{6cm} + \includegraphics[width=8cm]{c_100_next_neighbours_02.eps} + \begin{center} + \includegraphics[width=5cm]{c_100_res_bonds_vasp.ps} + \end{center} + \end{minipage} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Combination of defects + } + + \small + + Initial C \hkl<0 0 -1> insterstital at: $\frac{1}{4}\hkl<1 1 1>$ + + {\footnotesize + \begin{tabular}{|l|l|l|l|l|l|} + \hline + & 2 & 3 & 4 & 5 & 6 \\ + \hline +C \hkl<0 0 -1> & 6.23/-0.08 & 5.16/-1.15 & 6.23/-0.08 & 6.35/0.04 & 4.65/-1.66\\ + \hline +C \hkl<0 0 1> & 6.64/0.34 & 6.31/0.01 & 4.26/-2.05 & 6.57/0.26 & 4.78/-1.53 \\ + \hline +C \hkl<1 0 0> & 4.06/-2.25 & 6.13/-0.17 & 6.21/-0.10 & 6.03/-0.27 & 4.93/-1.38 \\ + \hline +C \hkl<-1 0 0> & \hkl<0 -1 0> & 4.41/-1.90 & 4.06/-2.25 & 6.19/-0.12 & 4.43/-1.88 \\ + \hline +C \hkl<0 1 0> & \hkl<1 0 0> & 5.95/-0.36 & \hkl<-1 0 0> & \hkl<-1 0 0> & \hkl<1 0 0> \\ + \hline +C \hkl<0 -1 0> & 3.92/-2.39 & 4.15/-2.16 & \hkl<1 0 0> & \hkl<1 0 0> & \hkl <-1 0 0> \\ + \hline +Vacancy & 1.39/-5.39 ($\rightarrow\text{ C}_{\text{S}}$) & 6.19/-0.59 & 3.65/-3.14 & 6.24/-0.54 & 6.50/-0.50 \\ + \hline +C$_{\text{sub}}$ & 4.80/0.26 & 4.03/-0.51 & 3.62/-0.93 & 4.39/-0.15 & 5.03/0.49 \\ +\hline + \end{tabular}\\[0.2cm] + } + + \begin{minipage}{8cm} + Energies: $x/y$\\ + $x$: Defect formation energy of the complex\\ + $y$: + $E_{\text{f}}^{\text{defect combination}}- + E_{\text{f}}^{\text{isolated C \hkl<0 0 -1>}}- + E_{\text{f}}^{\text{isolated 2nd defect}} + $\\[0.3cm] + {\color{blue} + If $y<0$ $\rightarrow$ favored compared to far-off isolated defects + } + \end{minipage} + \begin{minipage}{4.5cm} + \includegraphics[width=5.0cm]{00-1dc/energy.ps} + \end{minipage} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Combination of defects + } + + \small + + {\color{blue} + For defect position 3 and 5 (image 2 and 4) the unit cell is translated by + $\frac{a}{2} \hkl<0 -1 -1>$ + } + + Type of second defect: \hkl<0 0 -1> + + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/00-1_1.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/00-1_3.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/00-1_4.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/00-1_5.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/00-1_6.eps} + \end{minipage} + + \includegraphics[width=5.0cm]{00-1dc/energy_00x.ps} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Combination of defects + } + + \small + + {\color{blue} + For defect position 3 and 5 (image 2 and 4) the unit cell is translated by + $\frac{a}{2} \hkl<0 -1 -1>$ + } + + Type of second defect: \hkl<0 0 1> + + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/001_1.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/001_3.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/001_4.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/001_5.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/001_6.eps} + \end{minipage} + + \includegraphics[width=5.0cm]{00-1dc/energy_001.ps} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Combination of defects + } + + \small + + {\color{blue} + For defect position 3 and 5 (image 2 and 4) the unit cell is translated by + $\frac{a}{2} \hkl<0 -1 -1>$ + } + + Type of second defect: \hkl<1 0 0> or equivalent one + + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/100_1.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/100_3.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/100_4.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/100_5.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/100_6.eps} + \end{minipage} + + \includegraphics[width=5.0cm]{00-1dc/energy_100.ps} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Combination of defects + } + + \small + + {\color{blue} + For defect position 3 and 5 (image 2 and 4) the unit cell is translated by + $\frac{a}{2} \hkl<0 -1 -1>$ + } + + + Type of second defect: \hkl<-1 0 0> or equivalent one + + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/0-10_1.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/-100_3.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/-100_4.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/-100_5.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/0-10_6.eps} + \end{minipage} + + \includegraphics[width=5.0cm]{00-1dc/energy_x00.ps} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Combination of defects + } + + \small + + {\color{blue} + For defect position 3 and 5 (image 2 and 4) the unit cell is translated by + $\frac{a}{2} \hkl<0 -1 -1>$ + } + + Type of second defect: \hkl<0 1 0> or equivalent one + + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/100_1.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/010_3.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/-100_4.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/-100_5.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/100_6.eps} + \end{minipage} + + \includegraphics[width=5.0cm]{00-1dc/energy_010.ps} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Combination of defects + } + + \small + + {\color{blue} + For defect position 3 and 5 (image 2 and 4) the unit cell is translated by + $\frac{a}{2} \hkl<0 -1 -1>$ + } + + + Type of second defect: \hkl<0 -1 0> or equivalent one + + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/0-10_1.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/0-10_3.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/100_4.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/100_5.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/0-10_6.eps} + \end{minipage} + + \includegraphics[width=5.0cm]{00-1dc/energy_0x0.ps} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Combination of defects + } + + \small + + {\color{blue} + For defect position 3 and 5 (image 2 and 4) the unit cell is translated by + $\frac{a}{2} \hkl<0 -1 -1>$ + } + + Type of second defect: Vacancy + + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/vac_1.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/vac_3.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/vac_4.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/vac_5.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/vac_6.eps} + \end{minipage} + + \includegraphics[width=5.0cm]{00-1dc/energy_vac.ps} + +\end{slide} + +\begin{slide} + + {\large\bf\boldmath + Combination of defects + } + + \small + + {\color{blue} + For defect position 3 and 5 (image 2 and 4) the unit cell is translated by + $\frac{a}{2} \hkl<0 -1 -1>$ + } + + Type of second defect: C$_{\text{sub}}$ + + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/csub_1.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/csub_3.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/csub_4.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/csub_5.eps} + \end{minipage} + \begin{minipage}{2.5cm} + \includegraphics[width=2.5cm]{00-1dc/csub_6.eps} + \end{minipage} + + \includegraphics[width=5.0cm]{00-1dc/energy_csub.ps} + +\end{slide} + +\begin{slide} + + {\large\bf + Brainstorming: Point defects in Si (as grown and as implanted) + } + + \small + + Supercell size: $2$ -- $2000 \cdot 10^{-21}\text{ cm}^3$ + + \underline{After crystal growth} + \begin{itemize} + \item Si point defects at $450\, ^{\circ}\text{C}$ + \begin{itemize} + \item Interstitials: + \item Vacancies: + \end{itemize} + \item C impurities: $10^{17}\text{ cm}^{-3}$\\ + $\Rightarrow$ $10^{-4}$ -- $10^{-1}$ per sc + $\rightarrow$ neglected in simulations + \end{itemize} + + \underline{After/during implantation} + \begin{itemize} + \item Si point defects\\ + $E_{\text{d}}^{\text{av}}=35\text{ eV}$, + $D_{\text{imp}}=1\text{ -- }4 \cdot 10^{17}\text{ cm }^{-2}$, + $d_{\text{sc}}=3\text{ -- }30\cdot 4.38\text { \AA}$, + $A=(3\text{ -- }30\text{ \AA})^2$,\\ + Amount of collisions with $\Delta E > E_{\text{d}}$ + in depth region $[h,h+d_{\text{sc}}]$: $n=$ .. (SRIM)\\ + $\Rightarrow N_{\text{FP}}=nAD$ + \item C point defects + \begin{itemize} + \item Substitutional C: ... + \item Intesrtitial C: ... + \end{itemize} + \end{itemize} + +\end{slide} + +\begin{slide} + + {\large\bf + Reminder (just for me to keep in mind ...) + } + + \small + + \underline{Volume of the MD cell} + \begin{itemize} + \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$(T=0)$: $a_0=5.4575\text{ \AA}$ + $\rightarrow a(900\text{ K})=5.4674\text{ \AA}$ + \item C \hkl<1 0 0> in Si$(T=0)$: $a_0^{\text{avg}}= + \frac{1}{3}(a_0^x+a_0^y+a_0^z)=5.4605\text{ \AA}$ + $\rightarrow a(900\text{ K})=5.4704{ \AA}$ + \end{itemize} + Used in 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, no volume relaxation, scaled volume) + \item Use this configuration as the MD initial configuration + \end{itemize} + +\end{slide} + +\begin{slide} + + {\large\bf + Molecular dynamics simulations (VASP) + } + + 2 C atoms in $2\times 2\times 2$ Type 2 supercell at $450\,^{\circ}\text{C}$ + + \small + + \begin{minipage}{7.6cm} + Radial distribution\\ + \includegraphics[width=7.6cm]{md_02c_2222si_pc.ps} + \end{minipage} + \begin{minipage}{5.0cm} + \begin{center} + PC average from\\ + $t_1=50$ ps to $t_2=50.93$ ps + \end{center} + \end{minipage} + Diffusion: + \begin{itemize} + \item $<(x(t)-x(0))^2>$ hard to determine due to missing info of + boundary crossings + \item No jumps recognized in the + Video \href{../video/md_02c_2222si_vasp.avi}{$\rhd_{\text{local}}$ } $|$ + \href{http://www.physik.uni-augsburg.de/~zirkelfr/download/posic/md_02c_2222si_vasp.avi}{$\rhd_{\text{remote url}}$} + \end{itemize} + +\end{slide} + +\begin{slide} + + {\large\bf + Molecular dynamics simulations (VASP) + } + + 10 C atoms in $3\times 3\times 3$ Type 2 supercell at $450\,^{\circ}\text{C}$ + + \small + + \begin{minipage}{7.2cm} + Radial distribution (PC averaged over 1 ps)\\ + \includegraphics[width=7.0cm]{md_10c_2333si_pc_vasp.ps} + \end{minipage} + \begin{minipage}{5.0cm} + \includegraphics[width=6.0cm]{md_10c_2333si_pcc_vasp.ps} + \end{minipage} + Diffusion: + (Video \href{../video/md_10c_2333si_vasp.avi}{$\rhd_{\text{local}}$ } $|$ + \href{http://www.physik.uni-augsburg.de/~zirkelfr/download/posic/md_10c_2333si_vasp.avi}{$\rhd_{\text{remote url}}$}) + \begin{itemize} + \item $<(x(t)-x(0))^2>$ hard to determine due to missing info of + boundary crossings + \item Agglomeration of C? (Video) + \end{itemize} + +\end{slide} + +\begin{slide} + + {\large\bf + Molecular dynamics simulations (VASP) + } + + 1 C atom in $3\times 3\times 3$ Type 2 supercell at $900\,^{\circ}\text{C}$\\\\ + + Video \href{../video/md_01c_2333si_900_vasp.avi}{$\rhd_{\text{local}}$ } $|$ + \href{http://www.physik.uni-augsburg.de/~zirkelfr/download/posic/md_01c_2333si_900_vasp.avi}{$\rhd_{\text{remote url}}$}\\\\ + + \begin{itemize} + \item Inserted C becomes a \hkl<0 0 1> interstitial after a few femto-seconds + \item {\color{red}There is a non-zero total momentum!} + \item Migration of the C atom not observed + \item C \hkl<0 0 1> configuration persists + \end{itemize} + + Problem: Thermostat doesn't do momentum correction + + TODO: Start MD using relaxed (at zero temperature) initial configuration + +\end{slide} + +\begin{slide} + + {\large\bf + Molecular dynamics simulations (VASP) + } + + 10 C atoms in $3\times 3\times 3$ Type 2 supercell at $900\,^{\circ}\text{C}$ + + in progress ... + +\end{slide} + +\begin{slide} + + {\large\bf + Density Functional Theory + } + + Hohenberg-Kohn theorem + + \small + +\end{slide} + +\begin{slide} + + {\large\bf + More theory ... + } + + Transition state theory\\ + ART,NEB ... + + Group theory + + \small + +\end{slide} + +\end{document} \end{document}