[Pw_forum] wrong number of symmetries!

[Li Mingkai]

Actually, it's working after using ibrav=14 and  a,b,c and cosab, cosac,
cosbc. I just don't understand what happens. All vectors look good and just
some atoms' position are perturbated. Is it supposed not to check the
symmetry when I use nosym and nosym_vec?

CELL_PARAMETERS alat
6.930132 -2.310044 0.000000
0.000000 -6.930132 -2.310044
2.310044 0.000000 -6.930132
ATOMIC_SPECIES
  O 16 o_pbe_v1.2.uspp.F.UPF
  Zn 65.38 zn_pbe_v1.uspp.F.UPF
ATOMIC_POSITIONS crystal
  O 0.214285714285714 0.928571428571429 0.357142857142857
  Zn 0.625000000000000 0.625000000000000 0.625000000000000
  O 0.642857142857143 0.785714285714286 0.071428571428571
  Zn 0.053571428571429 0.482142857142857 0.339285714285714
  O 0.500000000000000 0.500000000000000 0.500000000000000
  Zn 0.910714285714286 0.196428571428571 0.767857142857143
  O 1.000000000000000 1.000000000000000 1.000000000000000
  Zn 0.410714285714286 0.696428571428572 0.267857142857143
  O 0.428571428571429 0.857142857142857 0.714285714285714
  Zn 0.839285714285714 0.553571428571429 0.982142857142857
  O 0.857142857142857 0.714285714285715 0.428571428571428
  Zn 0.267857142857143 0.410714285714286 0.696428571428571
  O 0.285714285714286 0.571428571428572 0.142857142857143
  Zn 0.696428571428572 0.267857142857143 0.410714285714286
  O 0.714285714285714 0.428571428571429 0.857142857142857
  Zn 0.125000000000000 0.125000000000000 0.125000000000000
  O 0.142857142857143 0.285714285714286 0.571428571428572
  Zn 0.553571428571429 0.982142857142857 0.839285714285714
  O 0.571428571428571 0.142857142857143 0.285714285714286
  Zn 0.982142857142857 0.839285714285715 0.553571428571428
  O 0.071428571428571 0.642857142857142 0.785714285714286
  Zn 0.482142857142857 0.339285714285714 0.053571428571429
  O 0.928571428571429 0.357142857142857 0.214285714285714
  Zn 0.339285714285714 0.053571428571429 0.482142857142857
  O 0.357142857142857 0.214285714285714 0.928571428571429
  Zn 0.767857142857143 0.910714285714285 0.196428571428572
  O 0.794990546871463 0.068336484376179 0.615028359385610
  Zn 0.196428571428572 0.767857142857143 0.910714285714286


Mingkai Li


On Sat, Oct 15, 2016 at 5:17 PM, Paolo Giannozzi <p.giannozzi at gmail.com>
wrote:

> (I was referring to symmetries of the lattice alone, not symmetries of the
> crystal; if you are sure that the crystal has no symmetries, commenting out
> the check should do the job)
>
> Il 15/ott/2016 11:13 AM, "Paolo Giannozzi" <p.giannozzi at gmail.com> ha
> scritto:
>
>> In order to find symmetries, the code uses a threshold to decide if a
>> rotated vector is the same as the original one. It may sometimes happen
>> that some "quasi-symmetries" are recognized as symmetries, some are not,
>> leading to a "symmetry group" that is not a group. This is likely what
>> happened in your case.  Paolo
>>
>> Il 15/ott/2016 01:27 AM, "Li Mingkai" <mingkaili at gmail.com> ha scritto:
>>
>>> I tried to do the scf calculation on a perturbated cell. I used
>>> "CELL_PARAMETERS alat" to specify vector. However, I got an error.
>>>
>>>  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>>> %%%%%%%%%%%%%%%%%%%
>>>      Error in routine set_sym_bl (3):
>>>      wrong number of symmetries! Use standard orientations for axis
>>>  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>>> %%%%%%%%%%%%%%%%%%%
>>>
>>> Since the cell is perturbated, there is no symmetry on it and space
>>> group should be P1. But it seemed that the pw.x tried to find some symmetry
>>> and got wrong number of symmetries. I tried nosym, nosym_vec, no_inv.
>>> Nothing works. I tried old version down to 5.0, which worked. After version
>>> 5.1, the error emergied. Of course, I tried to use celldm(1)~(6). It works
>>> well for all version. Since this input file is generated by a script
>>> automatically. I don't tend to modify the script a lot and try to figure
>>> out what happened before change everything.
>>>
>>> --
>>> Mingkai Li
>>> =======================================================
>>> School of Material Science and Engineering
>>> Hubei University
>>> Wuhan, Hubei Province
>>> P. R. China
>>> =======================================================
>>>
>>> _______________________________________________
>>> Pw_forum mailing list
>>> Pw_forum at pwscf.org
>>> http://pwscf.org/mailman/listinfo/pw_forum
>>>
>>
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>



-- 
Mingkai Li
=======================================================
Quantum-functional Semiconductor Research Center(QSRC)
Dongguk Univeristy, 3-26 Pil-dong, Joong-gu,
Seoul 100-715, Korea
Tel:(+82)-2-2260-3688
Fax:(+82)-2-2260-3945
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