sec checkin ... high T long t

diff --git a/posic/thesis/defects.tex b/posic/thesis/defects.tex
index 4164f87babab2b8b812d5fec0e5838897f7c0892..774d5df283ea31ca03baba2a6e2da883092d6f3d 100644 (file)
--- a/posic/thesis/defects.tex
+++ b/posic/thesis/defects.tex
@@ -1321,7 +1321,7 @@ In the same way the energetically most unfavorable configuration can be explaine
 The substitutional C is located next to the lattice site shared by the \hkl<1 1 0> Si self-interstitial along the \hkl<1 -1 0> direction.
 Thus, the compressive stress along \hkl<1 1 0> of the Si \hkl<1 1 0> interstitial is not compensated but intensified by the tensile stress of the substitutional C atom, which is no longer loacted along the direction of stress.
 
-{\color{red}Todo: Mig of C-Si DB conf to or from C sub + Si 110 int conf.}
+{\color{red}Todo: Mig of C-Si DB conf to or from C sub + Si 110 in progress.}
 
 \section{Migration in systems of combined defects}
 
@@ -1397,6 +1397,7 @@ At a displacement of 60 \% these bonds are broken.
 Due to this and due to the formation of new bonds, that is the bond of silicon atom number 1 to silicon atom number 5 and the bond of the carbon atom to its siliocn neighbour in the bottom left, a less steep increase of free energy is observed.
 At a displacement of approximately 30 \% the bond of silicon atom number 1 to the just recently created siliocn atom is broken up again, which explains the repeated boost in energy.
 Finally the system gains energy relaxing into the configuration of zero displacement.
+{\color{red}Todo: Direct migration of C in progress.}
 
 Due to the low binding energy observed, the configuration of the vacancy created at position 3 is assumed to be stable against transition.
 However, a relatively simple migration path exists, which intuitively seems to be a low energy process.

diff --git a/posic/thesis/md.tex b/posic/thesis/md.tex
index bb59f4f7ea18ccb1f0b83d08a52105f370640ed0..a6756d3e235a5d84579e52ea3745b731451d026d 100644 (file)
--- a/posic/thesis/md.tex
+++ b/posic/thesis/md.tex
@@ -15,6 +15,8 @@ Explain some more parameters that differ from the latter calculations ...
 
 Molecular dynamics simulations of a single, two and ten carbon atoms in $3\times 3\times 3$ unit cells of crytsalline silicon are performed.
 
+{\color{red}Todo: ... in progress ...}
+
 \section{Classical potential MD simulations}
 
 In contrast to the quantum-mechanical MD simulations the developed classical potential MD code is able to do constant pressure simulations using the Berendsen barostat.
@@ -465,17 +467,22 @@ The return to lower temperatures is considered seperately.
 Figure \ref{fig:md:95_long_time_v1} shows the evolution in time of the radial distribution for Si-C and C-C pairs for a low C concentration simulation.
 Differences are observed for both types of atom pairs indeed indicating proceeding structural changes even well beyond 100 ps of simulation time.
 Peaks attributed to the existence of substitutional C increase and become more distinct.
+This finding complies with the predicted increase of quality evolution as explained earlier.
+More and more C forms tetrahedral bonds to four Si neighbours occupying vacant Si sites.
 However, no increase of the amount of total C-C pairs within the observed region can be identified.
-Carbon, whether substitutional or as a dumbbell does not agglomerate within the simulated period of time.
+Carbon, whether substitutional or as a dumbbell does not agglomerate within the simulated period of time visible by the unchanging area beneath the graphs.
 
 Figure \ref{fig:md:95_long_time_v2} shows the evolution in time of the radial distribution for Si-C and C-C pairs for a high C concentration simulation.
 There are only small changes identifiable.
-Explain more ...
+A slight increase of the Si-C peak at approximately 0.36 nm attributed to the distance of substitutional C and the next but one Si atom along \hkl<1 1 0> is observed.
+In the same time the C-C peak at approximately 0.32 nm corresponding to the distance of two C atoms interconnected by a Si atom along \hkl<1 1 0> slightly decreases.
+Obviously the system preferes a slight increase of isolated substitutional C at the expense of incoherent C-Si-C precipitate configurations, which at a first glance actually appear as promising configurations in the precipitation event.
+On second thoughts however, this process of splitting a C atom out of this structure is considered necessary in order to allow for the rearrangement of C atoms on substitutional lattice sites on the one hand and for C diffusion otherwise, which is needed to end up in a structure, in which one of the two fcc sublattices is composed out of carbon only.
 
-For both, high and low concentration simulations the radial distribution converges as can be seen by the nearly identical graphs for the last two points in time.
+For both, high and low concentration simulations the radial distribution converges as can be seen by the nearly identical graphs of the two most advanced configurations.
 Changes exist ... bridge to results after cooling down to 20 degree C.
 
-{\color{red}Todo: Cooling down to 20 degree C and compare.}
+{\color{red}Todo: Cooling down to $20\,^{\circ}\mathrm{C}$ by $1\,^{\circ}\mathrm{C/s}$ in progress.}
  
 {\color{red}Todo: Remember NVE simulations (prevent melting).}
 
@@ -488,7 +495,7 @@ Since longer time scales are not sufficient \ldots
 {\color{red}Todo: other approaches?}
 
 {\color{red}Todo: ART MD?\\
-How about forcing a migration of a $V_2$ configuration to a constructed prec configuration, detrmine the maximum saddle point and let the simulation run?
+How about forcing a migration of a $V_2$ configuration to a constructed prec configuration, determine the saddle point configuration and continue the simulation from his configuration?
 }
 
 \section{Conclusions concerning the SiC conversion mechanism}