[Pw_forum] Mismatch in symmetry operations for diamond
Vahid Askarpour
vh261281 at dal.ca
Mon Sep 19 20:22:00 CEST 2016
Thanks Paolo. I will generate sr locally and that will solve my problem of transforming the electronic velocity vectors from the wedge to the whole BZ.
Best wishes,
Vahid
On Sep 19, 2016, at 3:12 PM, Paolo Giannozzi <p.giannozzi at gmail.com<mailto:p.giannozzi at gmail.com>> wrote:
Maybe rotation matrices in cartesian axis (sr) are not properly initialized, because not used, in EPW. The "historical" way of storing rotation matrices is in crystal axis and as integer matrices. By the way, I consider a very bad idea to have two distinct representations of the same matrices as global variables.
Paolo
On Mon, Sep 19, 2016 at 2:57 PM, Vahid Askarpour <vh261281 at dal.ca<mailto:vh261281 at dal.ca>> wrote:
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
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Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
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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
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