[gpaw-users] RPA: RuntimeWarning: invalid value encountered in sqrt

[Jens Jørgen Mortensen]

Den 11-11-2014 kl. 21:44 skrev Thomas Stenbæk Jauho:
> Hi,
>
> I am doing RPA calculations for Na and 30 other systems. I have 
> attached the scripts for Na, the RPA calculation is separated in three 
> separate files; a PBE calculation, a diagonalization and the RPA.
>
> While 30 systems do work, Na does not. I receive the following error:
>
> /home/niflheim/s093006/gpaw/gpaw/response/chi0.py:302: RuntimeWarning: 
> invalid value encountered in sqrt
> x_m = (-2 * df_m * deps_m / (omega.imag**2 + deps_m**2))**0.5
>
> I gather that it means that the square root (omega.imag**2 + 
> deps_m**2))**0.5 receives a negative argument, but I don't know why.
>
> Previously I experienced the same problem with Li, but I resolved the 
> issue by setting occupations=FermicDirac(0.01) i GPW(...) when making 
> the DFT calculation. But this does not help for the Na system.
>
> Any help will be highly appreciated!

This could have been fixed in the latest development version:

https://trac.fysik.dtu.dk/projects/gpaw/changeset/12121/trunk/gpaw/response/chi0.py

Could you try with the latests version - if you are not already using it?

Jens Jørgen

>
> /Thomas
>
>
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