[gpaw-users] GPAW PW crashes if ecut is too high

[Marcin Dulak]

Hi,

On 09/01/2013 12:26 AM, Rasmus Karlsson wrote:
> Hi!
> I just tried starting a PW calculation for relaxation of a unit cell 
> of CmC2_1 space group. However, GPAW immediately crashes with
> ../gpaw/wavefunctions/pw.py", line 37, in __init__
>     assert ((gd.h_cv**2).sum(1) <= 0.5 * pi**2 / ecut).all()
this is a known problem with skewed cells:
https://listserv.fysik.dtu.dk/pipermail/gpaw-developers/2012-May/002870.html
You need to set h manually (in addition to PW) to a very small value.

Best regards,

Marcin
>
> If running through with pdb, (gd.h_cv**2).sum(1) is
> array([ 0.05550866,  0.25919729,  0.25919729])
> and
> 0.5*pi**2/ecut is
> 0.22380475860123122
> Obviously, the second and third item in the array is too big. Reducing 
> the cutoff from 600 eV to 500 eV makes it work. This is somewhat strange.
>
> gd.h_cv is
> array([[  2.35602765e-01,   0.00000000e+00,   0.00000000e+00],
>        [  3.11742550e-17,   5.09114220e-01,   0.00000000e+00],
>        [  3.11742550e-17,  -4.50356897e-01,   2.37436210e-01]])
>
> Can anyone comment on what is going on? Am I doing something wrong, or 
> is GPAW behaving strangely?
>
> The calculation was run with v. 0.9.1.10258
>
> Thanks,
> Rasmus
>


-- 
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Marcin Dulak
Technical University of Denmark
Department of Physics
Building 307, Room 229
DK-2800 Kongens Lyngby
Denmark
Tel.: (+45) 4525 3157
Fax.: (+45) 4593 2399
email: Marcin.Dulak at fysik.dtu.dk

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