[gpaw-users] convergence issues

[Jens Jørgen Mortensen]

On Fri, 2011-01-21 at 16:08 +0100, Jens Jørgen Mortensen wrote:
> On Thu, 2011-01-20 at 13:27 -0800, Andrew Peterson wrote:
> > I'm trying three more things:
> > 
> > -the Co, Fe, and Ni calculations using MixerDif instead of the MixerSum. 
> > I'm using the default parameters for the _m keywords and am varying the 
> > other parameters as before (six parameters is too big for this sort of 
> > systematic parametric study)
> > 
> > -the Mn and Rh calculations with max SCF iterations (maxiter) set at 300 
> > instead of 120 in case any convergence parameters were making slow, 
> > steady progress
> > 
> > -the Mn and Rh calculations with 20 extra bands instead of 10 extra 
> > bands (nbands=-20)
> 
> I'll take a closer look, but for now I would say that all those clusters
> should converge with something like:
> 
> GPAW(xc='RPBE',
>      occupations=FermiDirac(0.01),
>      mixer=Mixer(0.02, 5, 100),
>      maxiter=300)

Hi again,

I tried to run all 16 clusters with the parameters above (see the
cluster13.py script) and all of them converged except Ni and Fe where I
had to use width = 0.1 eV.

If you decide to use GPAW for the course, then you might want to
consider using LCAO mode - this will give approximately a factor of ten
speed-up for your 13 atom clusters.

Jens Jørgen

> and MixerSum for Fe, Co and Ni.  Don't use the nbands keyword, unless
> you have a good reason to do it.  For metals with many states near the
> fermi-level it is important to include many empty bands.
> 
> Jens Jørgen
> 
> > Also, I'm attaching the scripts I used to generate the data in the PDF 
> > that Frank attached, in case there is anything in there I'm doing wrong. 
> > Looking forward to getting to the bottom of this!
> > 
> > Andy
> > 
> > Abild-Pedersen, Frank wrote:
> > > Hi Jens Joergen and Marcin
> > >
> > > Jens is teaching a course in electronic structure theory this spring and we have planned to use GPAW in the hands on part of the course.
> > > However, we are experiencing some convergence issues when we run the extremely simple systems we have chosen for the students.
> > > We run 13 atom clusters(Ag, Au, Cd, Cr, Cu, Ir, Mo, Os, Pd, Pt, Ru, W, Zn,Co, Fe, Mn, Ni, Rh).
> > > Below I attach the comments from and the very thorough study by Andrew.
> > >
> > > I've attached results of the calculations of the transition metals we
> > > discussed for the cluster project in GPAW/RPBE. There are loads of
> > > convergence issues. I took an Ansgar-type approach and varied the mixer
> > > parameters and eigensolver, in a total of 72 parameter combinations for
> > > each of the 18 metals. Of these, five metals (Co, Fe, Mn, Ni, Rh) did
> > > not converge with any of the 72 parameter combinations. (I used the
> > > MixerSum method for the ferromagnetics with the same parameters as the
> > > non-spin-polarized calculations.)
> > >
> > > Converged: Ag, Au, Cd, Cr, Cu, Ir, Mo, Os, Pd, Pt, Ru, W, Zn
> > > Did not converge: Co, Fe, Mn, Ni, Rh
> > >
> > > I also did bulk lattice constant calculations for all these metals in
> > > GPAW -- they are in the first table of the attachment. They all look
> > > pretty good and are close to the values that Felix previously calculated
> > > in Dacapo.
> > >
> > > It looks like we should use Dacapo for the class project, unless anyone
> > > has any ideas to achieve convergence that weren't reflected in my
> > > parametric study above. I have started the same cluster calculations
> > > with the Jacapo calculator -- I imagine they will all finish overnight
> > > and I can give an update on those results tomorrow.
> > >
> > > Andy
> > >
> > > Unless there is a simple solution that we have overlooked we will be forced to use Dacapo or Jacapo
> > > in all projects.
> > > Please send us comments/suggestions as soon as possible(hands on starts this tuesday).
> > >   
> > >
> > > ------------------------------------------------------------------------
> > >
> > 
> > plain text document attachment (input.template)
> > #!/usr/bin/env python
> > """Script to find the lattice constant for a given metal."""
> > 
> > import sys
> > sys.path.append('/nfs/slac/g/suncatfs/aap/usr/pylib')
> > 
> > from scipy.optimize import fmin
> > from ase.structure import bulk
> > from ase.visualize import view
> > from ase import io
> > from gpaw import GPAW, Mixer, MixerSum, MixerDif
> > from ase.optimize import QuasiNewton
> > 
> > from personal.ase import ParOpenCloseFile
> > 
> > output = ParOpenCloseFile('convergence data.txt')
> > write = output.write
> > 
> > 
> > ####### Make cluster.
> > def makecluster():
> >     atoms = io.read('Au13.traj')
> >     atoms.set_cell([20.,20.,20.])
> >     atoms.set_pbc((True, True, True))
> >     atoms.center()
> >     el = '${element}' # element
> >     if el in ['Fe', 'Ni', 'Co']:
> >         spinpol = True
> >     else:
> >         spinpol = False
> >     for atom in atoms:
> >         atom.set_symbol(el)
> >     return atoms, spinpol
> > 
> > ###### Convergence parameter space.
> > betas = [0.05, 0.1, 0.2, 0.3] 
> > nmaxolds = [3, 5, 7]
> > weights = [10., 50., 250.]
> > solvers = ['rmm-diis', 'cg']
> > 
> > 
> > ##### Calculation attempt.
> > def calculate(solver, beta, nmaxold, weight):
> >     atoms, spinpol = makecluster()
> >     """Attempt to calculate but don't abort script on failure."""
> >     if spinpol == True:
> >         for atom in atoms:
> >             atom.set_initial_magnetic_moment(1.1)
> >         mixer = MixerSum(beta=beta, nmaxold=nmaxold, weight=weight)
> >     else:
> >         mixer = Mixer(beta=beta, nmaxold=nmaxold, weight=weight)
> > 
> >     txt = 'gpawlog-%s-b%.2f-n%i-w%i.txt' % (solver, beta, nmaxold, weight)
> >     calc = GPAW(txt=txt,
> >                 h = 0.18,
> >                 xc = 'RPBE',
> >                 mixer = mixer,
> >                 width = 0.01,
> >                 stencils = (3,3),
> >                 nbands = -10,
> >                 kpts = [1, 1, 1],
> >                 spinpol = spinpol,
> >                 eigensolver = solver,
> >                 maxiter = 300,
> >                )
> >     atoms.set_calculator(calc)
> >     try:
> >         energy = atoms.get_potential_energy()
> >         iter = calc.get_number_of_iterations()
> >     except:
> >         energy = None
> >         iter = None
> >     return energy, iter
> > 
> > ###### Output.
> > def printline(header=False):
> >     """Prints an output line of text with convergence info."""
> >     goodformat = '%10s%10.2f%10i%10i%10.3f%10i\n'
> >     badformat =  '%10s%10.2f%10i%10i%10s%10s\n'
> >     headformat = '%10s%10s%10s%10s%10s%10s\n'
> >     if header:
> >         write(headformat % ('solver', 'beta', 'nmaxold',
> >                             'weight', 'energy', 'iter'))
> >     elif iter == None:
> >         write(badformat % (solver, beta, nmaxold, weight, '-', '-'))
> >     else:
> >         write(goodformat % (solver, beta, nmaxold, weight, energy, iter))
> > 
> > #### Run the space.
> > printline(header=True)
> > for solver in solvers:
> >     for beta in betas:
> >         for nmaxold in nmaxolds:
> >             for weight in weights:
> >                 energy, iter = calculate(solver, beta, nmaxold, weight)
> >                 printline()
> 
> _______________________________________________
> gpaw-users mailing list
> gpaw-users at listserv.fysik.dtu.dk
> https://listserv.fysik.dtu.dk/mailman/listinfo/gpaw-users
-------------- next part --------------
A non-text attachment was scrubbed...
Name: cluster13.py
Type: text/x-python
Size: 2120 bytes
Desc: not available
Url : http://listserv.fysik.dtu.dk/pipermail/gpaw-users/attachments/20110125/1c6767de/attachment.py