[Pw_forum] ERROR PROBLEM WITH SURFACE RELAXATION

[Ari P Seitsonen]

Dear Omamuyovwi Akemu,

   Please try breaking the symmetry, even slightly, in the top-most layer; 
the symmetry analysis apparently does not take into account the fixed 
coordinates. So initially the code thinks that the two surfaces are 
identical, but after the relaxation only the top-most layer is moved, 
making it different by symmetry from the other surface. I usually displace 
the surface layer atoms vertically just so much that the possible 
symmetries along the surface normal are broken.

   Or maybe this is not your problem...

     Greetings from Paris,

        apsi

-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
   Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
     Ecole Normale Supérieure (ENS), Département de Chimie, Paris
     Mobile (F) : +33 789 37 24 25    (CH) : +41 79 71 90 935


On Thu, 23 Jun 2016, Omamuyovwi Akemu wrote:

> Dear QE User,
>  
> I'm  having trouble trying to relax the (100) surface of Mo.
> I will be grateful if someone can help or give me a hint on how to fix this problem.
> Thanks you all.
> 
> Below is my input file:
> &CONTROL
>   calculation = "relax",
>   prefix      = "Mo"
>   pseudo_dir  = "/home/omamu/QE/espresso-5.0.1/pseudo",
>   outdir      = "./tmp",
> /
> &SYSTEM
>   ibrav       = 6,
>   celldm(1)   = 5.952639665D0,
>   celldm(3)   = 10.499999999D0,
>   nat         = 15,
>   ntyp        = 1,
>   ecutwfc     = 32.D0,
>   ecutrho     = 320.D0,
>   occupations = "smearing",
>   smearing    = "m-v",
>   degauss     = 0.02D0,
> /
> &ELECTRONS
>   conv_thr    = 1.D-8,
>   mixing_beta = 0.3D0,
> /
> &IONS
>   ion_dynamics   = 'bfgs'
> /
> ATOMIC_SPECIES
> Mo  95.94  Mo.pw91-n-van.UPF
> 
> ATOMIC_POSITIONS
> Mo   0.0000     0.0000     0.000   0  0  0
> Mo   0.5000     0.5000     0.500   0  0  0
> Mo   0.0000     0.0000     1.000   0  0  0
> Mo   0.5000     0.5000     1.500   0  0  0
> Mo   0.0000     0.0000     2.000   0  0  0
> Mo   0.5000     0.5000     2.500   0  0  0
> Mo   0.0000     0.0000     3.000   0  0  0
> Mo   0.5000     0.5000     3.500   1  1  1
> Mo   0.0000     0.0000     4.000   1  1  1
> Mo   0.5000     0.5000     4.500   1  1  1
> Mo   0.0000     0.0000     5.000   1  1  1
> Mo   0.5000     0.5000     5.500   1  1  1
> Mo   0.0000     0.0000     6.000   1  1  1
> Mo   0.5000     0.5000     6.500   1  1  1
> Mo   0.0000     0.0000     7.000   1  1  1
> 
> K_POINTS automatic
> 10  10   1   0  0  0
> 
> The error report is :
>   BFGS Geometry Optimization
> 
>      number of scf cycles    =   1
>      number of bfgs steps    =   0
> 
>      energy   new            =    -438.7514973224 Ry
> 
>      new trust radius        =       0.0549563359 bohr
>      new conv_thr            =       0.0000000100 Ry
> 
> 
> ATOMIC_POSITIONS (alat)
> Mo       0.000000000   0.000000000   0.000000000    0   0   0
> Mo       0.500000000   0.500000000   0.500000000    0   0   0
> Mo       0.000000000   0.000000000   1.000000000    0   0   0
> Mo       0.500000000   0.500000000   1.500000000    0   0   0
> Mo       0.000000000   0.000000000   2.000000000    0   0   0
> Mo       0.500000000   0.500000000   2.500000000    0   0   0
> Mo       0.000000000   0.000000000   3.000000000    0   0   0
> Mo       0.500000000   0.500000000   3.500000000
> Mo       0.000000000   0.000000000   4.000135262
> Mo       0.500000000   0.500000000   4.500756431
> Mo       0.000000000   0.000000000   4.999615948
> Mo       0.500000000   0.500000000   5.500355304
> Mo       0.000000000   0.000000000   6.000329230
> Mo       0.500000000   0.500000000   6.509232263
> Mo       0.000000000   0.000000000   6.993885956
> 
> 
> 
>  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>      Error in routine checkallsym (1):
>      some of the original symmetry operations not satisfied
>        
> Jolayemi Omamuyovwi Rita                                                                                                                            
?? ?                 
> Research Student
> University of Benin
> Nigeria.
> 
> 
>