+suggest an increased participation of Cs already in the initial stage
+of precipitation due to its high probability of incidence.
+
+slide 17
+
+as a last task, reproducing the SiC precipitation is attempted
+by successive insertion of 6000 C atoms,
+the number necessary to form a minimal precipitate,
+into a supercell consisting of 31 Si unit cells in each direction.
+insertion is realized at constant temperature.
+due to the high amount of particles,
+the classical potential must be used.
+since low carbon diffusion due to the overestimated barriers is expected,
+insertion volumes v2 and v3 next to the total volume v1 are considered.
+v2 corresponds to the minimal precipiatte size.
+v3 contains the amount of silicon atoms to form such a minimal precipitate.
+after insertion, the simulation is continued for 100 ps
+follwed by a cooling sequence downto 20 degrees celsius.
+
+slide 18
+
+the radial distribution function of simulations at 450 dc,
+an operative and efficient temperature in ibs, are shown.
+
+for the low C concentration simulation,
+a clearly 100 C-Si db dominated structure is obtained,
+which is obvious by comparing it to the
+reference distribution generated by a single Ci defect.
+the second peak is an artifact due to the cut-off.
+the C-C peak at 0.31 nm, as expected in cubic SiC,
+is generated by concatenated, differently oriented Ci dbs.
+the same distance is also expected for the Si atoms, and, indeed,
+the db structure stretches the Si-Si next neighbor distance,
+which is represented by nonzero values in the correlation function.
+
+so, the formation of Ci dumbbells indeed occurs.
+even the C atoms are already found in a separation as expected in cubic SiC.
+
+turning to the high C concentration simulations,
+a high amount of strongly bound C-C bonds
+as in graphite or diamond is observed.
+due to increased defect and damage densities
+defect arrangemnets are hard to categorize and trace.
+only short range order is observed.
+and, indeed, by comparing to other distribution data,
+an amorphous SiC-like phase is identified.
+
+slide 19
+
+to summarize, the formation of cubic SiC fails to appear.
+neither agglomeration of C interstitials
+nor a transition into SiC can be identified.
+
+slide 20
+
+having a closer look, there are two obvious reasons for this obstacle.
+
+first of all, there is the time scale problem inherent to md in general,
+which results in a slow phase space propagation due to
+a large amount of local minima separated by large energy barriers.
+accelerated methods, like temperature accelerated MD and so on, exist
+to bypass the time scale problem while retaining proper thermodynamic sampling.
+
+however, in addition, the overestimated diffusion barriers,
+due to the short range character of the potential,
+intensify this problem, which I termed:
+potential enhanced slow phase space propagation.
+
+the approach used in this study is to simply increase the temperature, however,
+without possible corrections.
+accelerated methods or higher time scales applied exclusively
+are assumed to be not sufficient.
+anyways, in this case,
+structural evolution instead of equilibrium properties are matter of interest.