X-Git-Url: https://hackdaworld.org/gitweb/?p=lectures%2Flatex.git;a=blobdiff_plain;f=posic%2Ftalks%2Fdefense.txt;h=79243cc7594edb4529e5db19482cb217afb34dab;hp=94350c3151a512abbb00e703fdc975a55b477c6d;hb=348f10f39655e4efc37eb22f88ac02c75ec60c23;hpb=b22bc79e3d45ce76a8b0f61c73b52ebdc5011ebb diff --git a/posic/talks/defense.txt b/posic/talks/defense.txt index 94350c3..79243cc 100644 --- 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