> > ###Ta substitution for Ti in STO is a n-type semiconductor. Think it > through.### > Yes sir. But i do not dope Ta directly. It's by way of nuclear > transmutation, Ta forms at site of Ti. Hafnium-181 (radioactive and a TDPAC > probe) is doped in STO. Hf-181 (stable OS: +4) decays into Ta-181 (stable > OS: +5). > Ta at a Ti site is a dopant. There are only two reasonable approximations: a) Ta "as is" (neutral cell), where the extra Ta n-type state may be localized or delocalized. Vanilla PBE may get this wrong. This models high Ta doping levels. b) A +ve charged cell (remove one electron) to model the n-type state being "elsewhere", i.e. a dilute limit.
Adding an electron makes little sense IMHO. > > I will try to repeat calculation with 6.5. > > Just one more thing, very recently i noticed that space group is not > mentioned in case.struct file after structure relaxation (case.struct file > already attached in previous mail). Do " x sgroup" need to run after > structrue relaxation also. > No > > -- Professor Laurence Marks Department of Materials Science and Engineering Northwestern University www.numis.northwestern.edu Corrosion in 4D: www.numis.northwestern.edu/MURI Co-Editor, Acta Cryst A "Research is to see what everybody else has seen, and to think what nobody else has thought" Albert Szent-Gyorgi
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