\documentclass[a4paper, oneside, 10pt]{article}
\usepackage[unicode]{hyperref}
\usepackage[utf8x]{inputenc}
\usepackage[english]{babel}
\usepackage{fixltx2e}
\date{\today}
\title{}
\author{}
\usepackage[utf8x]{inputenc}
\begin{document}



\subsection{\texorpdfstring{Phase Change Materials}{Phase Change Materials}}
\label{sec:phase_change_materials}


A \href{https://en.wikipedia.org/wiki/Phase-change_material}{phase change material} is a material
exhibiting easy and fast transition between \href{https://en.wikipedia.org/wiki/Crystal}{crystalline}
and \href{https://en.wikipedia.org/wiki/Amorphous_solid}{amorphous} phases. Due to this
characteristic, phase change materials have been used for rewritable
DVDs and Blueray disks, and are expected to be used for phase change
random access memory. Ge-Sb-Te compounds are major phase change
materials. We are performing molecular dynamics simulations to
identify amorphous phases of various Ge-Sb-Te compounds. Our
simulation data are analyzed to explore local atomic structures of
amorphous phases, which are compared with those of their crystalline
counterparts.

\subsubsection{\texorpdfstring{GeTe}{GeTe}}
\label{sec:gete}


We investigate structural properties of varius amorphous phases and crystalline using molecular dynamics simulation. Also, based on a Radial Distribution Functions(RDFs), Angle Distribution Functions(ADFs) and Order Parameters(OPs) analyses, we study local structure characteristics of several phases. Our calculated OPs and RDFs are analyzed and compared to EXAFS data available. Finally, we estimate energy barriers not only between crystalline and one of amorphous phases, but also between different amorphous phases to explore their structural stability, using nudged elastic band method.



\subsubsection{\texorpdfstring{GeSbTe225}{GeSbTe225}}
\label{sec:gesbte225}


The phase transition of Ge\textsubscript{2}Sb\textsubscript{2}Te\textsubscript{5} between its crystalline
and amorphous phases was investigated by constructing its various amorphous phases.



\subsubsection{\texorpdfstring{Sb\$\_2\$Te\$\_3\$}{Sb_2Te_3}}
\label{sec:sb_2te_3}


Sb$_2$Te$_3$ is a very interesting material for rewritable optical media. We study of the switching mechanism between the amorphous and crystal states theoretically.



\begin{center}
\line(1,0){250}
\end{center}



\end{document}
