finisched albe, go on with ensemble control

[lectures/latex.git] / posic / thesis / basics.tex

diff --git a/posic/thesis/basics.tex b/posic/thesis/basics.tex
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--- a/posic/thesis/basics.tex
+++ b/posic/thesis/basics.tex
@@ -204,16 +204,22 @@ Details of the Tersoff potential derivative are presented in appendix \ref{app:d
 \subsubsection{Improved analytical bond order potential}
 
 Although the Tersoff potential is one of the most widely used potentials there are some shortcomings.
 \subsubsection{Improved analytical bond order potential}
 
 Although the Tersoff potential is one of the most widely used potentials there are some shortcomings.

-Describing the Si interaction Tersoff was unable to find a single parameter set to describe well both, bulk and surface properties.
+Describing the Si-Si interaction Tersoff was unable to find a single parameter set to describe well both, bulk and surface properties.

 Due to this and since the first approach labeled T1 \cite{tersoff_si1} turned out to be unstable \cite{dodson87}, two further parametrizations exist, T2 \cite{tersoff_si2} and T3 \cite{tersoff_si3}.
 While T2 describes well surface properties, T3 yields improved elastic constants and should be used for describing bulk properties.
 However, T3, which is used in the Si/C potential, suffers from an underestimation of the dimer binding energy.
 Due to this and since the first approach labeled T1 \cite{tersoff_si1} turned out to be unstable \cite{dodson87}, two further parametrizations exist, T2 \cite{tersoff_si2} and T3 \cite{tersoff_si3}.
 While T2 describes well surface properties, T3 yields improved elastic constants and should be used for describing bulk properties.
 However, T3, which is used in the Si/C potential, suffers from an underestimation of the dimer binding energy.

-Similar behavior is found for the C interaction.
+Similar behavior is found for the C-C interaction.

 
 

-For this reason, Erhart and Albe provide a reparametrization of the Tersoff potential based on three independently fitted potentials for the Si-Si, C-C and Si-C interaction \cite{albe_sic_pot}.
-The functional form is nearly the same like the one proposed by Tersoff.
+For this reason, Erhart and Albe provide a reparametrization of the Tersoff potential based on three independently fitted parameter sets for the Si-Si, C-C and Si-C interaction \cite{albe_sic_pot}.
+The functional form is similar to the one proposed by Tersoff.

 Differences in the energy functional and the force evaluation routine are pointed out in appendix \ref{app:d_tersoff}.
 Differences in the energy functional and the force evaluation routine are pointed out in appendix \ref{app:d_tersoff}.

-For Si ...
+Concerning Si the elastic properties of the diamond phase as well as the structure and energetics of the dimer are reproduced very well.
+The new parameter set for the C-C interaction yields improved dimer properties while at the same time delivers a description of the bulk phase similar to the Tersoff potential.
+The potential provides succeeds in the description of the low as well as high coordinated structures is provided.
+The description of elastic properties of SiC is improved with respect to the potentials available in literature.
+Defect properties are only fairly reproduced but the description is comparable to previously published potentials.
+It is claimed that the potential enables the modeling of widely different configurations and transitions among these and has recently been used to simulate the inert gas condensation of Si-C nanoparticles \cite{erhart04}.
+Therefore the Erhart/Albe (EA) potential is considered the superior analytical bond order potential to study the SiC precipitation and associated processes in Si.

 
 \subsection{Statistical ensembles}
 \label{subsection:statistical_ensembles}
 
 \subsection{Statistical ensembles}
 \label{subsection:statistical_ensembles}