The ABINIT Users Mailing List ( CLOSED )

[matthieu verstraete <mjv500@york.ac.uk>]

> Dear Experts,
Dear disciple,

> fact that the matrix elements are complex in general. As I go along the line
> of the 2*nband*nband printed elements,
>
> 1) are the real and imaginary parts of the matrix elements printed in pairs
> one after the other, or are all the nband*nband real parts printed first,
> and then all imaginary parts, or somehow else?
yes: real(eig1_1,1) imag(eig1_1,1)   real(eig1_2,1) imag(eig1_2,1)
...

eig1 is the 1st order eigenvalue (matrix) and _2,1 are the indices.


> 2) what band index is changed first (the inner loop): of the k+q
> wavefunctions or of the k wavefunctions (for matrix elements <k+q|V|k>)?
You can confirm what I write above in the abinit subroutine that 
calculates the eig1. See in particular cgwf3.F90:

> >
    !The array eig1_k contains  
<u_(iband,k+q)^(0)|H_(k+q,k)^(1)|u_(band,k)^(0)>
     do iband=1,nband
      eig1_k(2*iband-1 +(band-1)*2*nband)=scprod(1,iband)
      eig1_k(2*iband   +(band-1)*2*nband)=scprod(2,iband)
     end do
<<

so the fast index is on k+q.

Matthieu