[Pw_forum] How to optimize the BaTiO3 tetragonal structure?

[Mojtaba Mirseraji]

Dear All

How to optimize the BaTiO3 tetragonal structure?
Because when I use minimum energy and zero pressure, I face to very
different lattice parameters (celldm(1) and celldm(3)) in comparison
to experiment and even DFT calculations!!!!!!! I used
PZ/PW91/PBE/PBESOL but all of them were different!!!!!1
more reports are a=3.990 to 4.00 and c/a is 1.011 to 1.013 but my
calculations are very different!!!!!!!!!

Is my procedure for optimization correct? if it is not, please guide me.
an example of relaxation is attached

Regards

Mojtaba Mirseraji
Ph.D. Candidate, Theoretical Condensed Matter Physics
Arak Univ.
I.R.IRAN
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