From: hackbard Date: Fri, 10 Jul 2009 16:06:32 +0000 (+0200) Subject: weekend commit :) X-Git-Url: https://hackdaworld.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=308a99aefd361f2e795db24e852574f91758a9df;p=lectures%2Flatex.git weekend commit :) --- diff --git a/posic/talks/upb-ua-xc.tex b/posic/talks/upb-ua-xc.tex index e95c0fb..502375b 100644 --- a/posic/talks/upb-ua-xc.tex +++ b/posic/talks/upb-ua-xc.tex @@ -218,7 +218,7 @@ POTIM = 0.1 \begin{itemize} \item Calculation of cohesive energies for different lattice constants \item No ionic update - \item tetrahedron method with Blöchl corrections for + \item Tetrahedron method with Blöchl corrections for the partial occupancies $f_{nk}$ \item Supercell 3 (8 atoms, 4 primitive cells) \end{itemize} @@ -269,7 +269,7 @@ POTIM = 0.1 \begin{itemize} \item Calculation of cohesive energies for different lattice constants \item No ionic update - \item tetrahedron method with Blöchl corrections for + \item Tetrahedron method with Blöchl corrections for the partial occupancies $f_{nk}$ \end{itemize} \vspace*{0.6cm} @@ -379,6 +379,49 @@ POTIM = 0.1 \end{slide} +\begin{slide} + + {\large\bf + Used types of supercells\\ + } + + \footnotesize + + \begin{minipage}{4.3cm} + \includegraphics[width=4cm]{sc_type0.eps}\\[0.3cm] + \underline{Type 0}\\[0.2cm] + Basis: fcc\\ + $x_1=(0.5,0.5,0)$\\ + $x_2=(0,0.5,0.5)$\\ + $x_3=(0.5,0,0.5)$\\ + 1 primitive cell / 2 atoms + \end{minipage} + \begin{minipage}{4.3cm} + \includegraphics[width=4cm]{sc_type1.eps}\\[0.3cm] + \underline{Type 1}\\[0.2cm] + Basis:\\ + $x_1=(0.5,-0.5,0)$\\ + $x_2=(0.5,0.5,0)$\\ + $x_3=(0,0,1)$\\ + 2 primitive cells / 4 atoms + \end{minipage} + \begin{minipage}{4.3cm} + \includegraphics[width=4cm]{sc_type2.eps}\\[0.3cm] + \underline{Type 2}\\[0.2cm] + Basis: sc\\ + $x_1=(1,0,0)$\\ + $x_2=(0,1,0)$\\ + $x_3=(0,0,1)$\\ + 4 primitive cells / 8 atoms + \end{minipage}\\[0.4cm] + + {\bf\color{blue} + In the following these types of supercells are used and + are possibly scaled by integers in the different directions! + } + +\end{slide} + \begin{slide} {\large\bf @@ -403,10 +446,52 @@ POTIM = 0.1 -E_{\textrm{coh}}^{\textrm{initial conf}}\Big) N \] } - - \begin{center} + Influence of supercell size\\ + \begin{minipage}{8cm} \includegraphics[width=7.0cm]{si_self_int.ps} - \end{center} + \end{minipage} + \begin{minipage}{5cm} + $E_{\textrm{f}}^{\textrm{110},\,32\textrm{pc}}=3.38\textrm{ eV}$\\ + $E_{\textrm{f}}^{\textrm{tet},\,32\textrm{pc}}=3.41\textrm{ eV}$\\ + $E_{\textrm{f}}^{\textrm{hex},\,32\textrm{pc}}=3.42\textrm{ eV}$\\ + $E_{\textrm{f}}^{\textrm{vac},\,32\textrm{pc}}=3.51\textrm{ eV}$ + \end{minipage} + +\end{slide} + +\begin{slide} + + {\large\bf + Questions so far ...\\ + } + + What configuration to chose for C in Si simulations? + \begin{itemize} + \item Switch to another method for the XC approximation (GGA, PAW)? + \item Reasonable cut-off energy + \item Switch off symmetry? (especially for defect simulations) + \item $k$-points + (Monkhorst? $\Gamma$-point only if cell is large enough?) + \item Switch to tetrahedron method or Gaussian smearing ($\sigma$?) + \item Size and type of supercell + \begin{itemize} + \item connected to choice of $k$-point mesh? + \item hence also connected to choice of smearing method? + \item constraints can only be applied to the lattice vectors! + \end{itemize} + \item \ldots + \end{itemize} + +\end{slide} + +\begin{slide} + + {\large\bf + Review (so far) ...\\ + } + + + \end{slide}