From: hackbard Date: Wed, 4 May 2011 09:34:38 +0000 (+0200) Subject: started to add stuff to basics chapter, sec checkin X-Git-Url: https://hackdaworld.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=577ac1dd49cfae5402672d068b4a2ab5f8a72758;p=lectures%2Flatex.git started to add stuff to basics chapter, sec checkin --- diff --git a/posic/thesis/basics.tex b/posic/thesis/basics.tex index ac43367..fdc82f6 100644 --- a/posic/thesis/basics.tex +++ b/posic/thesis/basics.tex @@ -1,15 +1,30 @@ \chapter{Basic principles of utilized simulation techniques} +\label{chapter:basics} + +In the following the simulation methods used within the scope of this study are introduced. +Enabling the investigation of the evolution of structure on the atomic scale, molecular dynamics simulations were chosen in order to model the behavior and precipitation of C introduced into an initially crystalline Si environment. +To be able to model systems with a large amount of atoms computational efficient classical potentials to describe the interaction of the atoms are most often used in MD studies. +For reasons of flexibility in executing this non-standard task and in order to be able to use a novel interaction potential \cite{albe_sic} an appropriate MD code called {\em posic ({\bf P}recipitation {\bf o}f {\bf SiC})}\footnote{The source code will be made available for download at http://www.physik.uni-augsburg.de/~zirkelfr/posic/posic.tar.bz2} including a library collecting respective MD subroutines was developed from scratch. +The basic ideas of MD in general and the adopted techniques as implemented in {\em posic} in particular are outlined in section \ref{section:md}, while the functional form and derivative of the employed classical potential is presented in appendix \ref{app:d_tersoff}. +An overview of the most important tools within the MD package is given in appendix \ref{app:code}. +In addition to the classical potential approach ... +Highly accurate technique DFT, VASP code, VASP mods, tools in appendix ... + +Determining the formation energies if defects is ... + +Migration pathways were investigated using the , which is explained in cloder detail in ... + + +\section{Molecular dynamics simulations} +\label{section:md} \begin{quotation} \dq We may regard the present state of the universe as the effect of the past and the cause of the future. An intellect which at any given moment knew all of the forces that animate nature and the mutual positions of the beings that compose it, if this intellect were vast enough to submit the data to analysis, could condense into a single formula the movement of the greatest bodies of the universe and that of the lightest atom; for such an intellect nothing could be uncertain and the future just like the past would be present before its eyes.\dq{} -\cite{laplace} \begin{flushright} -{\em Marquis Pierre Simon de Laplace, 1814.} +{\em Marquis Pierre Simon de Laplace, 1814, \cite{laplace}.} \end{flushright} \end{quotation} -\section{Molecular dynamics simulations} - Pierre Simon de Laplace phrased this vision in terms of a controlling, omniscient instance - the {\em Laplace demon} - which would be able to look into the future as well as into the past due to the deterministic nature of processes, governed by the solution of differential equations. Although Laplace's vision is nowadays corrected by chaos theory and quantum mechanics, it expresses two main features of classical mechanics, the determinism of processes and time reversibility of the fundamental equations. This understanding was one of the first ideas for doing molecular dynamics simulations, considering an isolated system of particles, the behaviour of which is fully determined by the solution of the classical equations of motion.