You should first of all verify whether the quantity you print depends upon the specific choice of irreps/degeneracies/phases of wavefunctions/phases of the moon. If you are really sure that the quantity you print should not vary across versions, a safe but slow way to figure out what happened when and maybe why is to start from a svn version close to 4.0.3 and go up until something happens.
Paolo On Fri, Jun 26, 2015 at 8:23 PM, Samuel Poncé <[email protected]> wrote: > Dear developers of QE, > > I noticed a backward compatibility issue on the electron-phonon matrix > element between QE 4.0.3 and 5.1.2. > > I was wondering if it was a bug and if not, what was the reason. > > I added the following line in the two versions of the code in > PHonon/PH/elphon.f90 > > if (ik==215) then > > write(*,*)'elphmat(:,:,:)**2',SUM((REAL(REAL(elphmat(:,:,:))))**2)+SUM((REAL(AIMAG(elphmat(:,:,:))))**2) > > This should be a physically relevant quantity that should not change > between version (the order of the mode changed but it is not an issue). > > Test: > 6x6x6 q-grid same pseudo, tol and inputs parameters > > There is 16 irr q-points: > > ( 16q-points): > N xq(1) xq(2) xq(3) > 1 0.000000000 0.000000000 0.000000000 > 2 -0.166666667 0.166666667 -0.166666667 > 3 -0.333333333 0.333333333 -0.333333333 > 4 0.500000000 -0.500000000 0.500000000 > 5 0.000000000 0.333333333 0.000000000 > 6 -0.166666667 0.500000000 -0.166666667 > 7 0.666666667 -0.333333333 0.666666667 > 8 0.500000000 -0.166666667 0.500000000 > 9 0.333333333 0.000000000 0.333333333 > 10 0.000000000 0.666666667 0.000000000 > 11 0.833333333 -0.166666667 0.833333333 > 12 0.666666667 -0.000000000 0.666666667 > 13 0.000000000 -1.000000000 0.000000000 > 14 0.666666667 -0.333333333 1.000000000 > 15 0.500000000 -0.166666667 0.833333333 > 16 -0.333333333 -1.000000000 0.000000000 > > All the elphmat**2 are the same (up to 4 digits) for 13 of the 16 > q-points. For example > > QE 5.1.2 q = ( -0.166666667 0.166666667 -0.166666667 ) > elphmat(:,:,:)**2 0.5446267 > elphmat(:,:,:)**2 0.5446253 > elphmat(:,:,:)**2 0.9506719 > elphmat(:,:,:)**2 0.9506719 > > freq ( 1) = 9.137536 [THz] = 304.795384 [cm-1] > freq ( 2) = 9.137536 [THz] = 304.795384 [cm-1] > freq ( 3) = 15.052865 [THz] = 502.109513 [cm-1] > freq ( 4) = 39.653912 [THz] = 1322.712114 [cm-1] > freq ( 5) = 39.653912 [THz] = 1322.712114 [cm-1] > freq ( 6) = 40.741956 [THz] = 1359.005377 [cm-1] > > QE 4.0.3 q = ( -0.166666667 0.166666667 -0.166666667 ) > elphmat(:,:,:)**2 0.5446267 > elphmat(:,:,:)**2 0.9506719 > elphmat(:,:,:)**2 0.5446266 > elphmat(:,:,:)**2 0.9506719 > > omega( 1) = 9.137611 [THz] = 304.799915 [cm-1] > omega( 2) = 9.137611 [THz] = 304.799915 [cm-1] > omega( 3) = 15.052641 [THz] = 502.105399 [cm-1] > omega( 4) = 39.653770 [THz] = 1322.716173 [cm-1] > omega( 5) = 39.653770 [THz] = 1322.716173 [cm-1] > omega( 6) = 40.741800 [THz] = 1359.009209 [cm-1] > > > But the three irr-q* 5, 10* and *16* are NOT the same: > QE 5.1.2 q = ( 0.000000000 0.333333333 0.000000000 ) > elphmat(:,:,:)**2 0.1192376 > elphmat(:,:,:)**2 0.9861287 > elphmat(:,:,:)**2 1.348592 > elphmat(:,:,:)**2 0.3134981 > > freq ( 1) = 11.633039 [THz] = 388.036416 [cm-1] > freq ( 2) = 11.633039 [THz] = 388.036416 [cm-1] > freq ( 3) = 16.188917 [THz] = 540.004156 [cm-1] > freq ( 4) = 39.110566 [THz] = 1304.588071 [cm-1] > freq ( 5) = 39.110566 [THz] = 1304.588071 [cm-1] > freq ( 6) = 40.947507 [THz] = 1365.861806 [cm-1] > > QE 4.0.3 q = ( 0.000000000 0.333333333 0.000000000 > elphmat(:,:,:)**2 0.3075966 > elphmat(:,:,:)**2 1.354492 > elphmat(:,:,:)**2 0.1192375 > elphmat(:,:,:)**2 0.9861288 > > omega( 1) = 11.633152 [THz] = 388.042751 [cm-1] > omega( 2) = 11.633152 [THz] = 388.042751 [cm-1] > omega( 3) = 16.188922 [THz] = 540.007888 [cm-1] > omega( 4) = 39.110425 [THz] = 1304.592025 [cm-1] > omega( 5) = 39.110425 [THz] = 1304.592025 [cm-1] > omega( 6) = 40.947359 [THz] = 1365.865939 [cm-1] > > As you can see the difference for the 0,1/3,0 is not huge but significant. > As a matter of fact when > I'm using the dvscf produced by QE 4 or 5 for that irr-q it can lead to > physically very different results. Therefore I would like to know which > dvscf file is correct (QE 4 or 5)? > > Thank you, > > Best Regards, > > Samuel Ponce > Department of Materials, University of Oxford > > > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum > -- Paolo Giannozzi, Dept. Chemistry&Physics&Environment, Univ. Udine, via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222
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