[Pw_forum] electron phonon interaction in ph.x

[degironc]

Dear Jin Zhang,
       we are probably saying the same thing... just notice that 
dyn(*,*)  array
after the call to routine dyndia  IS NOT the dynamical matrix anymore 
but contains
the eigenvectors...
       best,
              stefano

Jin Zhang wrote:

> I did a test in phonon.f90. The code is sth like this:
>
>   USE ions_base, only : nat,amass
>   complex(dp), allocatable :: work(:,:)
>   allocate(work(3*nat,3*nat))
>  
>   DO ipert = 1,3*nat
>      DO jpert = 1,3*nat
>         DO i=1,3*nat
>         work(ipert,jpert) = work(ipert,jpert) + 
> conjg(dyn(i,ipert))*amass(1)*dyn(i,jpert)
>         ENDDO
>      ENDDO
>   ENDDO
>   write(*,*) 'dynmat:'
>   write(*,"(6(f12.8))") work(:,:)
>   deallocate(work)
> ------------------------------------------
> The output for example07 is:
>   1.00000000  0.00000000  0.00000000  0.00000000  0.00000000  0.00000000
>   0.00000000  0.00000000  1.00000000  0.00000000   0.00000000  0.00000000
>   0.00000000  0.00000000  0.00000000  0.00000000  1.00000000  0.00000000
>  The relation dyn^{\diag} * amass * dyn = I sustains indeed.
>  Actually we're talking about the same thing. The inner product of 
> eigenvector U^{\diag} M U gives scalar 1.
>  While dyn^{\diag} * amass * dyn gives unit matrix.
>
> On 12/1/06, *degironc* <degironc at sissa.it <mailto:degironc at sissa.it>> 
> wrote:
>
>     Jin Zhang wrote:
>
>     > 2. dyn(iat, jat): The dynamical matrix which obeys -- dyn^{\diag} *
>     > amass * dyn = 1
>
>     I don't think dymanical matric should obey this relation...
>
>     EIGENVECTORS,  U,  of the generalized problem Dyn U = M U
>     omega^2  will obey
>     U^\dagger M U = 1 or something like that...
>     while
>     EIGENVECTORS, V=\sqrtM U of problem 1/sqrtM Dyn 1/sqrtM V = omega^2 V
>     will obey V^\dagger V = 1
>
>     stefano
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