[Pw_forum] Mismatch in symmetry operations for diamond

[Vahid Askarpour]

Hi Paolo,

I printed the other s(:,:,isym) and got the following for some of them:

for s(3)
  1.00000000000000       0.000000000000000E+000  0.000000000000000E+000
  0.000000000000000E+000  -1.00000000000000       0.000000000000000E+000
  0.000000000000000E+000  0.000000000000000E+000  -1.00000000000000
 instead of
 cart.    s( 3) = ( -1.0000000  0.0000000  0.0000000 )
                  (  0.0000000  1.0000000  0.0000000 )
                  (  0.0000000  0.0000000 -1.0000000 )

for s(4)
   1.00000000000000       0.000000000000000E+000  0.000000000000000E+000
  0.000000000000000E+000   1.00000000000000       0.000000000000000E+000
  0.000000000000000E+000  0.000000000000000E+000  -1.00000000000000
 instead of
 cart.    s( 4) = (  1.0000000  0.0000000  0.0000000 )
                  (  0.0000000 -1.0000000  0.0000000 )
                  (  0.0000000  0.0000000 -1.0000000 )
for s(5)
   1.00000000000000       0.000000000000000E+000  0.000000000000000E+000
  0.000000000000000E+000   1.00000000000000       0.000000000000000E+000
  0.000000000000000E+000  0.000000000000000E+000  -1.00000000000000
instead of
 cart.    s( 5) = (  0.0000000  1.0000000  0.0000000 )    f =( -0.2500000 )
                  (  1.0000000  0.0000000  0.0000000 )       (  0.2500000 )
                  (  0.0000000  0.0000000 -1.0000000 )       (  0.2500000 )

The following two lines are included at the top of the routine:

  USE symm_base, ONLY : s, sr,nsym,t_rev, time_reversal, set_sym_bl, nrot
  USE cell_base, ONLY : alat, at, omega,bg

Interestingly, I get the correct symmetries if in the same EPW routine, I do the following (from the symm_base.f90):

  DO isym = 1,nsym
     sa (:,:) = dble ( s(:,:,isym) )
     sb = matmul ( bg, sa )
     sr (:,:, isym) = matmul ( at, transpose (sb) )
    write(*,*) sr(:,:,isym)
  ENDDO

Somehow, sr needs to be recalculated and it is not enough to include USE symm_base and cell_base at the top of the routine.

Best,

Vahid


On Sep 19, 2016, at 8:37 AM, Vahid Askarpour <vh261281 at dal.ca<mailto:vh261281 at dal.ca>> wrote:

Hi Paolo,

I was attempting to extract the symmetries in an EPW routine in order to simplify the calculations. I used a loop ns=1,nrot and inside this loop, I printed sr(:,:,2). Perhaps I should have looped over nsym instead of nrot. I will check to see if this makes a difference.

Thanks,

Vahid


On Sep 19, 2016, at 2:57 AM, Paolo Giannozzi <p.giannozzi at gmail.com<mailto:p.giannozzi at gmail.com>> wrote:

What is printed on output is exactly sr(:,:,isym), with isym running over symmetries. Where and how did you print sr(:,:,2)? and what about all other symmetries?

Paolo

On Mon, Sep 19, 2016 at 12:28 AM, Vahid Askarpour <vh261281 at dal.ca<mailto:vh261281 at dal.ca>> wrote:
Dear QE Users,

When doing relaxation on diamond, one of the symmetry operations identified by QE-5.4.0 is the following:

isym =  2     180 deg rotation - cart. axis [0,0,1]

cryst.   s( 2) = (     0          1         -1      )
                       (     1          0         -1      )
                       (     0          0         -1      )

 cart.    s( 2) = ( -1.0000000  0.0000000  0.0000000 )
                       (  0.0000000 -1.0000000  0.0000000 )
                       (  0.0000000  0.0000000  1.0000000 )

However, when I print out sr(:,:,2) for this structure (isym=2), I get :

  1.00000000000000                0.000000000000000E+000   0.000000000000000E+000
  0.000000000000000E+000  -1.00000000000000                0.000000000000000E+000
  0.000000000000000E+000    0.000000000000000E+000   1.00000000000000

Since the sr matrix prints the cartesian rotation matrix, there seems to be a mismatch between the sr(1,1) elements. The other elements are consistent.

Is this a bug or am I missing another operation embedded in the sr matrix?

Thank you,

Vahid

Vahid Askarpour
Department of Physics and Atmospheric Science
Dalhousie University,
Halifax, NS, Canada


_______________________________________________
Pw_forum mailing list
Pw_forum at pwscf.org<mailto:Pw_forum at pwscf.org>
http://pwscf.org/mailman/listinfo/pw_forum



--
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

_______________________________________________
Pw_forum mailing list
Pw_forum at pwscf.org<mailto:Pw_forum at pwscf.org>
http://pwscf.org/mailman/listinfo/pw_forum

_______________________________________________
Pw_forum mailing list
Pw_forum at pwscf.org<mailto:Pw_forum at pwscf.org>
http://pwscf.org/mailman/listinfo/pw_forum

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20160919/1de23eeb/attachment.html>