I do not think the routine you mention should have any effect whatsover, unless you introduce a supercell (as in old-fashioned "mass approximation").
Paolo On Tue, Nov 15, 2016 at 1:49 PM, Antoine JAY <[email protected]> wrote: > Dear Paolo Giannozzi and community, > > This 4*4*4 is important because it modifies the "total_weight" variable. > > Example: > I did an interpolation of a 5^3 q-mesh to calculate the phonon DOS. > I get the error message: > > frc_blk, wrong total_weight > > because the condition > ABS(total_weight-nr1*nr2*nr3).GT.1.0d-8) of matdyn.f90/subroutine > frc_blk > is not fulfilled. > in frc_blk, nr1, nr2 and nr3 have been changed through read_ifc_param and > are each 5 as asked in ph.in. > > But the total_weight was 124.1 and not 125. > This is due to the fact that total_weight is calculated through variables > that are in the subroutine q_gen which uses fixed nr: > INTEGER, PARAMETER:: nr1=4, nr2=4, nr3=4 > > When I change in q_gen > INTEGER, PARAMETER:: nr1=5, nr2=5, nr3=5 > > the total_weight changes and is exactly 125 > and the condition was fulfilled so that the phonon DOS run without any > error. > > What hypothesis did you do to keep these variables fixed? > Am I doing something wrong? > > > Antoine JAY > > > > > > > I think 4x4x4 is not directly related to the q-point grid, but to the > maximum size of the supercell (if you want to build a supercell with force > constants computed in the unit cell. It was used once upon a time in > GaAs/AlAs heterostructure, I think) > > > Paolo > > On Tue, Nov 15, 2016 at 9:00 AM, Antoine JAY < > [email protected]> > wrote: > > > Dear community and developers, > > > > Looking at the code of qe_6.0 > > > > I am wondering why in PHonon/PH/matdyn.f90 > > subroutine q_gen > > > > the values nr1, nr2 and nr4 are fixed to be 4: > > INTEGER, PARAMETER:: nr1=4, nr2=4, nr3=4 > > > > whereas they should be fixed as nr1=nq1, nr2=nq2, and nr3=nq3. > > as done by the first call of read_ifc_param(nr1, nr2, nr3). > > > > Is there a physical meaning? > > Is this subroutine right if someone don't whant a 4^3 q-mesh? > > > > Antoine Jay > > _______________________________________________ > Pw_forum mailing list > [email protected] > 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
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