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

Dear WD Duan,

The strain and homogeneous electric field perturbations have  
(naturally) zero wavevector,
as mentioned in the ERROR message that you get.
So, please, use qpt 0.0 0.0 0.0 to compute electric field and strain  
response functions.
There are lots of examples in the corresponding tutorials. E.g. for  
ABINITv5 see the entry tutorial page
http://www.abinit.org/Infos_v5.2/tutorial/welcome.html .

Xavier Gonze

On 20 Oct 2006, at 17:59, abinit_duan@126.com wrote:

> Dear Horacio Wagner Leite Alves,
>        Firstly, thanks a lot for your help. I have calculated the  
> phonon spectrum successfully when "qpt" is set to (0.5  0.0  0.0),  
> but at the same condition when I compute the response function to  
> "electric field" and "strain",some thing is wrong as following:
>   "getcut: wavevector=  0.0000  0.0000  0.0000  ngfft=  18  18  18
>          ecut(hartree)=      6.000   => boxcut(ratio)=   2.07835
>  ==>  initialize data related to q vector <==
>  respfn : ERROR -
>   The treatment of non-zero wavevector q is restricted to phonons.   
> However, the input normalized qpt is    5.000000E-01    0.000000E 
> +00    0.000000E+00,
>   while rfelfd= 2, and rfstrs= 0.
>   Action : change qpt, or rfelfd or rfstrs in the input file."
> I do not know how to deal with it. So I wonder if we could  
> calculate the response functions to "electric field" and "strain",  
> if it can be calculated, how? Would you mind sending me some  
> example of this kind?
> Thanks in advance!
> WD Duan