[Pw_forum] ERROR PROBLEM WITH SURFACE RELAXATION

[Paolo Giannozzi]

The alternative is to remove constraints that break the symmetry. The
code assumes that the structural optimization conserves the original
symmetry, which is true, but only in the absence of symmetry-breaking
constraints.

On Thu, Jun 23, 2016 at 6:48 PM, Ari P Seitsonen <Ari.P.Seitsonen at iki.fi> wrote:
>
> 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.
>>
>>
>
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222