[gpaw-users] BEEF gas-phase convergence

[Jess Wellendorff]

Hi AJ,

sorry I didn't reply your previous email.

So, gas-phase CO is in my experience not a problem in GPAW.
Are you using a very large unit cell?
Can I see the txt output from the calculation?

The following script converges CO with BEEF-vdW in about 20 iterations 
in a somewhat small cell:
************
from ase import *
from gpaw import GPAW, FermiDirac
from ase.structure import molecule

xc = 'BEEF-vdW'
name = 'co_'+str(xc)

sys = molecule('CO')
sys.set_cell([5.1, 5.2, 7.0])
sys.center()

calc = GPAW(nbands=-2,
             h=0.18,
             xc=xc,
             occupations=FermiDirac(0.0),
             txt=name+'.txt')
sys.set_calculator(calc)
sys.get_potential_energy()
************

I would really like to see the output from your calculations.

Best,
Jess

On 11/12/2012 12:41 AM, Andrew Medford wrote:
> Hi all,
>
> I am having an extremely difficult time converging gas-phase CO with
> BEEF. I have tried extensive combinations of mixing parameters,
> different basis sets, grid-spacings, periodic boundary conditions,
> etc. and nothing will converge. The errors tend to almost converge,
> stagnate for ~10 iterations, then oscillate away. This will repeat for
>> 500 iterations.
> I assume that gas-phase CO must have been converged during the fitting
> of BEEF, so it must be possible. Any hints on what I might be doing
> wrong?
>
> Best wishes,
>
> AJ
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