[gpaw-users] beef error

[Manuel Šaric]

Regarding H2O(g) with BEEF-vdW.

One should be able to do this:
"""
from ase import Atoms, Atom
from ase.optimize import QuasiNewton
from gpaw import GPAW, FermiDirac, Mixer
from ase.visualize import view
from gpaw.eigensolvers.davidson import Davidson
from ase.io import read, write

name = 'H2O'

cell = (12, 12, 12)
periodic = (0, 0, 0)

h2o = Atoms([Atom('O', position=(0, 0, 0)),
	     Atom('H', position=(1, 0, 0)),
	     Atom('H', position=(0, 1, 0))], cell=cell, pbc=periodic)
h2o.center()
view(h2o)

h = 0.18
nbands = -10
xc = 'BEEF-vdW'
mixer = Mixer(0.05, 5 , weight=50.0)
eigensolver = Davidson(niter=2)

calc = GPAW(h=h,
	    xc=xc,
	    mixer=mixer,
	    eigensolver=eigensolver,
	    nbands=nbands,
	    txt='%s.txt' % name)

h2o.set_calculator(calc)

dyn = QuasiNewton(h2o, trajectory='%s.traj' % name,  logfile='%s.log' % name)
dyn.run(fmax=0.05)

calc.write('%s.gpw' % name)
"""
Should work for O2(g) as well.

I remember having problems when I tried using a larger cell with pbc = ((1, 1, 1))

Hope it helps
______________________________________
From: Marcin Dulak
Sent: Wednesday, February 25, 2015 1:02 PM
To: Logi Arnarson; gpaw-users at listserv.fysik.dtu.dk; Manuel Šaric
Subject: RE: beef error

Hi,

the calculation scf does not converge.
I believe this is a common problem with the BEFF-vdw functional for molecules,
see http://listserv.fysik.dtu.dk/pipermail/gpaw-users/2014-May/002686.html
I would try to set width=0.1 eV and check you don't get fractional occupancies in the solution.
Manuel: how do you converge molecules with BEEF-vdw?

Best regards,

Marcin
________________________________
From: Logi Arnarson [logi at au.dk]
Sent: Wednesday, February 25, 2015 9:24 AM
To: gpaw-users at listserv.fysik.dtu.dk
Subject: beef error

Dear GPAW Users,

I am trying to estimate the error of a formation energy calculation using the the BEEF-vdw functional. The calculation is for a Vanadia Oxide species on a surface (VO3H/TiO2) where the VO3H is calculated with respect to V2O5(b) and H2O(g).
In the script (see script.txt) I therefore read the respective gpw files in order to get the potential energies. Then I get KohnShamConvergenceError for the H2O calculation (see error.txt). I have done analogous beef calculation for a VO3 species where instead of having H2O(g) as the reference but O2(g) which doesn't  give rise to an error. The calculations for H2O(g) and O2(g) are done in exactly the same way.

Is there someone out there who might know how to fix this?

Regards,
Logi

--
Logi Arnarson
PhD Student
iNANO, AArhus University