[gpaw-users] beef error

[Jess Wellendorff]

One could also try to start from a converged GGA calculation, eg. PBE or 
revPBE. This should give a fast and very good initial guess for the 
BEEF-vdW electron density. Might even save time since the GGA SCF steps 
are faster than the BEEF-vdW ones. It's very easy to switch to BEEF-vdW 
after a converged GGA run:

h2o.calc.set(xc='BEEF-vdW')

- Jess

On 02/27/2015 11:23 AM, Manuel Šaric wrote:
> 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
>
>
>
>
>
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