[gpaw-users] Error in response calculation

[Falco Hüser]

sorry, I overlooked that you are using k-point parallelization, so 16 
cores would be fine.
But try increasing ecut. For very unevenly shaped unit cells, a low 
cutoff can result in a too small number of G vectors.

On 08/26/2014 10:06 AM, Falco Hüser wrote:
> Hi Glenn,
>
> can you try using less CPUs? You are running on 16 cores, which is 
> absolutely not necessary, and there are only 5 G vectors (plane 
> waves). The code uses a mixed frequency/G vector parallelization, so 
> maybe some cores just get an empty matrix, which cannot be diagonalized.
> Anyway, your plane wave energy cutoff seems very low (12 eV), increase 
> it for a larger number of plane waves.
>
> Falco
>
> On 08/26/2014 09:54 AM, Glenn Jones wrote:
>>
>> Hi,
>>
>> I am starting to use the response module in GPAW for calculating 
>> absorption spectra of TM oxides.
>>
>> Non-spin polarised calculations worked fine, but I am now running 
>> into some issues with spin polarised calculations, that aren’t so 
>> well documented:
>>
>> I have pre optimised my bulk system which is read in from out.gpw 
>> (which I am unable to send by email because it is too big).  However 
>> on running the following script I get a ‘Singular matrix error’ – see 
>> attached .txt file for the full output:
>>
>> from ase.io import read
>>
>> import numpy as np
>>
>> from gpaw import GPAW, FermiDirac, Mixer
>>
>> from ase import Atom, Atoms
>>
>> from ase.visualize import view
>>
>> from gpaw.mixer import Mixer
>>
>> from gpaw.response.df import DF
>>
>> from gpaw.mpi import world
>>
>> ABS = 1
>>
>> if ABS:
>>
>>     df = DF(calc='../out.gpw',
>>
>>             q=np.array([0.0, 0.0, 0.00001]),
>>
>>             w=np.linspace(0,10,200),
>>
>>             eta=0.05,
>>
>>             ecut=12,
>>
>>             optical_limit=True,
>>
>>             xc='ALDA_X'
>>
>>             #kcommsize=4
>>
>>             )
>>
>>     df.get_absorption_spectrum()
>>
>> ____________________________________________________________
>>
>> Any clues as to how to get around this would be appreciated,
>>
>>
>> Thanks,
>>
>>
>> Glenn
>>
>>
>>
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