more tomorrow!

[lectures/latex.git] / posic / talks / defense.txt

diff --git a/posic/talks/defense.txt b/posic/talks/defense.txt
index 94350c3..79243cc 100644 (file)
--- a/posic/talks/defense.txt
+++ b/posic/talks/defense.txt
@@ -224,8 +224,9 @@ slide 10
 
 defect structures are obtained by creating a supercell of crystalline silicon
 with periodic boundary conditions and temperature and pressure set to zero.
-the interstitial carbon or silicon atom is inserted followed by
-structural relaxation into a local minimum configuration.
+the interstitial carbon or silicon atom is inserted,
+for example at the tetrahedral or heexagonal site,
+followed by structural relaxation into a local minimum configuration.
 
 next to the structure, defects can be characterized by formation energies,
 which is defined by this formula, where the chemical potential
@@ -247,7 +248,16 @@ each step the configurational energy of the relaxed structure is recorded.
 
 slide 11
 
-
+in the following, structures and formation energies
+of silicon self-interstitial defects are shown.
+the classical potential and ab initio method predict formation energies,
+which are within the same order of magnitude.
+however, discrepancies exist.
+quantum-mechanical results reveal the silicon 110 interstitial dumbbell (db)
+as the ground state closely followed by the hexagonal and tetrahedral
+configuration, which is the consensus view for silicon interstitials.
+in contrast, the ea potential favors the tetrahedral configuration,
+a known problem, which arises due to the cut-off ...
 
 slide 12
 slide 13