[Pw_forum] cell optimization

[Eyvaz Isaev]

Dear Hania,

First of all I would recommend you read at least
Richard Martin's textbook. There are also nice review
papers of W.Pickett (old, but good to understand the
basic ideas), S.Baroni et al. (2002, Rev.Mod.Phys),
Arias et al. in  RMP (?) etc.......

I suggest your problem raised by "ATOMIC_POSITIONS  "
keyword. By default it is "alat", i.e. atomic
positions are in units of the lattice parameter "a". 
But looking at atomic positions provided it seems you
use Angstrom. I.e. you used cartesian coordiantes in
Angstrom.
So, use ATOMIC_POSITIONS  {angstrom} and see what
happens.

Bests,
Eyvaz.

>  
>  
>  &control    calculation  = 'scf'    restart_mode =
> 'from_scratch'    pseudo_dir   =
> '/root/pwscf/pseudo/'    outdir       = '/root/tmp/'
> / &system    ibrav=7    celldm(1)=7.33,
> celldm(3)=8.54    nat=19    ntyp=3    ecutwfc=25.0  
>  ecutrho=100.0 / &electrons    conv_thr = 1e-6,   
> mixing_beta=0.2,
>     startingwfc=’random’ /ATOMIC_SPECIES  Bi   
> 208.98    Bi.pbe-d-mt.UPF  Ti    47.867   
> Ti.pbe-sp-van_ak.UPF  O     15.9994  
> O.pbe-van_ak.UPFATOMIC_POSITIONS  Bi 0.00000000
> 0.00000000 0.5713404 Bi 0.00000000 0.00000000
> 7.9816596 Bi 0.00000000 0.00000000 1.8072489 Bi
> 0.00000000 0.00000000 6.7457511 Ti 0.00000000
> 0.00000000 3.1757289 Ti 0.00000000 0.00000000
> 5.3772711 Ti 0.00000000 0.00000000 4.2765000 O 
> 0.50000000 0.00000000 0.0000 O  0.00000000
> 0.50000000 0.0000 O  0.50000000 0.00000000 2.13825 O
>  0.50000000 0.00000000 6.41475 O  0.00000000
> 0.00000000 3.771873 O  0.00000000 0.00000000
> 4.781127 O  0.00000000 0.00000000 2.7241305 O 
> 0.00000000 0.00000000 5.8288695 O  0.50000000
> 0.00000000 1.0049775 O  0.50000000 0.00000000
> 7.5480225 O  0.00000000 0.50000000 1.0049775 O 
> 0.00000000 0.50000000 7.5480225K_POINTS {automatic} 
> 4 4 4 1 1 1 
>  
 

-------------------------------------------------------------------
Prof. Eyvaz Isaev, 
Theoretical Physics Department, Moscow State Institute of Steel & Alloys, Russia, 
Department of Physics, Chemistry, and Biology (IFM), Linkoping University, Sweden 
Condensed Matter Theory Group, Uppsala University, Sweden 
Eyvaz.Isaev at fysik.uu.se, isaev at ifm.liu.se, eyvaz_isaev at yahoo.com