# [Pw_forum] phonon elph espresso 3.2

Andrea Floris afloris at physik.fu-berlin.de
Fri Mar 2 10:55:22 CET 2007

```Dear Paolo and Malgorzata, thank you for your help.

Summarizing:

With ldisp=.true. (automatic q grid)
if one does the sequence of calculation
1) pw.x scf (with 'la2F=.true.')  2) pw.x scf (with la2F=.false.)  (at
k-mesh good enough for phonons, as in example07)  3) ph.x for phonon and
elph, then I don't get errors (with a sensible choice of grids:)

With ldisp=.false. (q by hand) :
if one does the sequence of calculation
1) pw.x scf (with 'la2F=.true.')  2) pw.x phonon (to diagonalize in ek
e(k+q) 3) ph.x phonon and elph, then I don't get errors.

With ldisp=.false. (q by hand) :
if one does the sequence of calculation
1) pw.x scf (with 'la2F=.true.')  2) pw.x scf (with la2F=.false.)  (at
k-mesh good enough for phonons, as in example07)  3) ph.x for phonon and
elph, then I get the error
from phq_init : error #         1
wrong order of k points

Then there is the example that you reported below (i.e. with
'lnscf=.true.'),
that seems to  produce the same error.
-------

Moreover: in my previous mail I said wrongly that the interpolation of the
elph
matrix elements was done in the subroutine lint. It is actually done in
PH/clinear.f90. Sorry for this.

Relative to PH/clinear.f90, I have a question:
can you confirm that
noint(1) noint(2) noint(3)...noint(nkfit) are the interpolated matrix
elements associated
respectively to the k point in crystal coordinates in this order: 000,
001, 002....010
011...100 101....nk1fit-nk2fit-nk3fit ?

ciao, grazie
Andrea

> From: Paolo Giannozzi <giannozz at nest.sns.it>
> Subject: Re: [Pw_forum] phonon elph espresso 3.2
> Date: Thu, 1 Mar 2007 15:08:31 +0100
> To: pw_forum at pwscf.org
>
>
> On Feb 22, 2007, at 11:50 , Andrea Floris wrote:
>
> > In any case with this meshes I get the error
> >           1           2           4
> >
> >   0.500000000000000      -0.500000000000000       0.500000000000000
> >  -0.250000000000000       0.250000000000000      -0.250000000000000
> >   0.000000000000000E+000  0.000000000000000E+000  0.000000000000000E
> > +000
>
> >      from phq_init : error #         1
> >      wrong order of k points
>
> I see: it is the option 'lnscf=.true.' that does not work as expected
> (i.e. it doesn't work at all). It will be fixed very soon.
>
> Paolo
>
> ---
> Paolo Giannozzi, Democritos and University of Udine, Italy

```