[Wien] problem with init_phonon_lapw

[Peter Blaha]

I don't think there is any problem with your calculations.

Aparently you generated (properly ?) a supercell which consists of 64 atoms.
Than one atom is displaced and the nn program found out, that even after
this displacement some of the atoms are still equivalent and wants to
regroup the 64 atoms into some other set.

I'd assume that everything is ok and you should follow the suggestion of
init_lapw and accept the new struct_nn file. (Be sure to use the latest
ini_lapw!)

The only part which could be different from a "normal" setup is that you
should NOT follow the suggestion of SGROUP, when it changes the
lattice type (lattice parameters,...), because from this reduced cell
the analyse_phonon script might not be able to reconstruct the forces
for all atomes in the original supercell.

> Hello Wien users,
> I have been trying to resolve a problem with phonon lapw (including writing to this site). I would much appreciate any suggestions. 
> I have generated a supercell (.d45) file using the software Phonon. The system is cubic SiC ( supercell contains 64 atoms). The input data used were the minimum obtained after volume optimisation with Wien2k (a=b=c= 4.129142 Ang). In Phonon I used : No. of non-eq. elastic: 0
> No. of non-eq. displacive particles : 2
> Supercell : 2x2x2
> The .d45 file was then transferred to Wien2k. 
> After running init_phonon_lapw with the options RMT = 1.6 (we got this RMT after volume optimisation)and atom number range 1-64 we get the error :
>  Mult not equal Please check outputnn
> ityp not equal Please check outputnn
> In output nn file I find that the number of inequivalent atoms has changed from 64 to 24.
> Please suggest what I could do
> Thanks in advance,
> Chandrika
> 


                                      P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/theochem/
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