The ABINIT Users Mailing List ( CLOSED )

["Dr. Aldo Romero" <aromero@qro.cinvestav.mx>]

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Dear Michel

it is not a big secret, here I am including the cell optimization, the
final spacegroup is 166. Then, I input the optimized parameters in the
phonon calculation but now the space group is 12...

Probably is related to some precision issue but I have not been able to
figure it out.

With respect to stability, I can say that a) experimentally is stable at
that pressure b) the same problem also happens at 1GPa
c) the cell parameters at high pressure looks "very similar" to the 0
pressure case.

I hope somebody can give me an advice on how to proceed.

Regards

- -aldo.


- -------------------------------------------
Prof. Aldo Humberto Romero
CINVESTAV-QUERETARO
Libramiento Norponiente No 2000
Real de Juriquilla
76230 Queretaro, Qro, Mexico

email:  aromero@qro.cinvestav.mx
        aldo@ipicyt.edu.mx
Phone:  (52)-442-441 4909
Fax: (52) 442 441 4938



Michel Côté wrote:
> Hello Aldo,
> 
> Maybe your system is unstable at high pressure? It will help to know exactly
> what you are working on if it is not a state secret! As always, you should
> include your input file.
> 
> Michel 
> 
> 
> Le 26/03/07 09:46, « Matthieu Verstraete » <mjv500@york.ac.uk> a écrit :
> 
>> I'm not sure, the rprim look ok, but you have to check with the space
>> group. Angles, etc are also output by abinit, you can check those, and I
>> don't know if the xred are supposed to be highly symmetrical (0.25 or if
>> there value is correct)...
>>
>> good luck!
>>
>> Matthieu
>>
>> On Sun, 25 Mar 2007, Dr. Aldo wrote:
>>
>>>> Dear Matthieu,
>>>>
>>>> thanks for your kind reply. I did your suggested changes and the
>>>> system is still changing the symmetry.. this is quite surprising....
>>>>
>>>> Now my input includes
>>>>
>>>> acell    3*7.9899636324E+00
>>>>
>>>> rprim    5.7005417584E-01  0.0000000000E+00  8.2160710438E-01
>>>>        -2.8502708792E-01  4.9368140048E-01  8.2160710438E-01
>>>>        -2.8502708792E-01 -4.9368140048E-01  8.2160710438E-01
>>>>
>>>> xred    3*2.4055724610E-01
>>>>       3*-2.4055724610E-01
>>>>
>>>> Is there any other relation that the a(i,j) should follow?..
>>>>
>>>> Just to give you an example, I did the zero pressure calculation
>>>> and the symmetry is fine and the parameters for that case are
>>>>
>>>> xred 2.3464570938E-01  2.3464570938E-01  2.3464570938E-01
>>>>    -2.3464570938E-01 -2.3464570938E-01 -2.3464570938E-01
>>>> acell 8.3880824458E+00  8.3880824458E+00  8.3880824458E+00
>>>> rprim 5.5906349543E-01  0.0000000000E+00  8.2912484469E-01
>>>>      -2.7953174771E-01  4.8416318937E-01  8.2912484469E-01
>>>>      -2.7953174771E-01 -4.8416318937E-01  8.2912484469E-01
>>>>
>>>>
>>>> Sorry that I am emailing you to yoru account.. I hope it is Ok.
>>>>
>>>> Best regards and thanks in advance
>>>>
>>>> -aldo.
>>>>
>>>>
>>>>
> 
> 
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kptopt 1
prtvol 1

nstep 1000
ntime 1000
toldff  1.0d-10
nshiftk 1
shiftk 0.0  0.0 0.0
optcell   2
ionmov  2
tolmxf 1.0d-8
dilatmx 1.2
ecutsm 0.5

strtarget  3*-.00023792502459040098 3*0.0

so_typat  2
nspinor  2

nband 24

xred    2.3920727770E-01  2.3920727770E-01  2.3920727770E-01
        -2.3920727770E-01 -2.3920727770E-01 -2.3920727770E-01

rprim 5.5906349543E-01  0.0000000000E+00  8.2912484469E-01
     -2.7953174771E-01  4.8416318937E-01  8.2912484469E-01
     -2.7953174771E-01 -4.8416318937E-01  8.2912484469E-01

acell 8.0754081560E+00  8.0754081560E+00  8.0754081560E+00

ecut  25.0d0
natom  2
ngkpt    8 8 8
tsmear 0.002
ntypat  1
occopt  7
ntypat  1
occopt  7
typat  1 1
znucl 51.0
enunit 2

ndtset 5

  getden 3
  getwfk 3
  kptopt 3
    nqpt 1
   iscf 3
#Dataset 1 : SCF with small number of k points

  getden1  0
  getwfk1  0
  kptopt1  1
    nqpt1  0
  prtden1  1
  tolvrs1  1.0d-14
#Dataset 2 : non-SCF for all k points
  getden2  1
  getwfk2  1
    iscf2 -2
    nqpt2  0
  tolwfr2  1.0d-22
#Dataset 3 : SCF with large number of k points
  getden3  1
  getwfk3  2
    iscf3  3
    nqpt3  0
  prtden3  1
  tolvrs3  1.0d-14
#Dataset
    iscf4 -2
  tolwfr4  1.0d-22
qpt4       0.041666667    0.041666667    0.041666667
#Dataset 5 : RF
  getwfq5  4
 rfatpol5  1 1
   rfdir5  1 1 1
  rfphon5  1
  toldfe5  1.0d-8
qpt5       0.041666667    0.041666667    0.041666667

so_typat  2
nspinor  2
nband 24
nshiftk 1
shiftk 0.0  0.0 0.0

acell    3*7.9899636324E+00
rprim    5.7005417584E-01  0.0000000000E+00  8.2160710438E-01
        -2.8502708792E-01  4.9368140048E-01  8.2160710438E-01
        -2.8502708792E-01 -4.9368140048E-01  8.2160710438E-01
xred    3*2.4055724610E-01
       3*-2.4055724610E-01

ecut  25.0d0
natom  2

ngkpt    8 8 8

ecutsm 0.5
tsmear 0.002
nstep 2000
ntime 2000
ntypat  1
occopt  7
typat  1 1
znucl 51.0
enunit 2