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[Xavier Gonze <gonze@pcpm.ucl.ac.be>]

Dear Deyu Lu,

In most of ABINIT, double precision is used for both real and complex  
data.
Some part of GW subroutines use simple precision, but this is the  
exception...

Regards,
Xavier

On 20 May 2006, at 02:42, dylu@ucdavis.edu wrote:

> Hello, I've a question regarding the precision of complex  
> variables, such as
> omega and epsilon in a GW calculation. I'm kind of confused by the  
> way they are handled. To be specific, in the routine to evaluate  
> plasmon pole parameters "cppm1par.F90", they are declared as single  
> precision:
>
> complex,intent(in) :: epsm1(npwvec,npwvec,nomega,nq),omega(nomega)
>
> Before being written into a SCR file, however, they are converted  
> to double precision in wrscr.F90
>
>      complex,intent(in) :: epsm1(npwsigx,npwsigx,nomega),omega(nomega)
>      complex (kind(0.0d0)),allocatable :: epsm1d(:,:),omegad(:)
> ......
>        omegad(:) = omega(:)
>        epsm1d(:,:) = epsm1(:,:,io)
>
> I'm wondering if complex data are treated as single precision in  
> the main codes of  abinit. If it is the case, it would deteriorate  
> the GW results.
>
> Thanks
> Deyu