[Pw_forum] Which Pseudopotential is good for relaxing BaTiO3? Help me please

[Mojtaba Mirseraji]

Dear Saad

I used your suggestion but unfortunately a is about 4.2 angstrom was achieved.
I relaxed it to zero pressure and minimum energy.
I do not know how to do !!!!!!!!!

Thanks

On 3/12/15, saad sarwar <saadsarwar111 at yahoo.com> wrote:
> you should use
> Ba_lda_v1.uspp.F.UPF
> Ti_lda_v1.uspp.F.UPFO_lda_v1.2.uspp.F.UPF
>
>
>      On Thursday, March 12, 2015 9:45 PM, Mojtaba Mirseraji
> <quantum.pwscf at gmail.com> wrote:
>
>
>  Dear Paolo and all users
>
> I want to relax the structures of tetragonal and cubic BaTiO3 (barium
> titanate)
> But when I use some pseudopotentials, I can not reach the correct
> lattice parameters.
> Unfortunately, I calculate a=4.100 to 4.200 for cubic structure of
> BaTiO3 but all articles reported that "a" is about 4.006 and my
> results are very different !!!!!!!!!!!!!!
> Also, for tetragonal structure a=3.800 to 3.900 and c/a=1.250 to 1.265
> !!!!!!!!!!!!!!
> but this is reported in some articles, a=3.991 and c/a=1.011
> !!!!!!!!!!!!!!!
>
> I used some pseudopotentials such as pz (for PSLibrary, both rrkjus
> and kjpaw), pw91 (for PSLibrary, both rrkjus and kjpaw), relpw91 (for
> PSLibrary, both rrkjus and kjpaw), pw91 (for Vanderbilt, US) and ....
> !!!!!!!!!!!!!
> All these did not calculate correctly both lattice parameters and
> polarizations, unfortunately !!!!!!!!!!!
>
> Which pseudopotential is good for this job? give me some suggestions, please
> !!!
> In general, I am very disappointed to QE and pseudopotentials
>
> Thanks in advance
>
> Mojtaba Mirseraji
> Ph.D. Candidate, theoretical condensed matter physics
> Arak Univ.
> I.R.IRAN
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