[Wien] convergence problem :: runsp_c_lapw

[Luis Ogando]

Dear Prof. Marks,

   Just a quick question: if someone reduce the greed to a very low value
but go back to the default values in case.inm for the last iterations, is
it safe ?
   All the best,
           Luis


2014-04-24 9:15 GMT-03:00 Laurence Marks <L-marks at northwestern.edu>:

> Why did you change case.inm away from the defaults?
>
> a) Set the greed to 0.2 not 0.005. As I have said before, this does
> not do what you think it does and concepts such as "reduce the mixing
> factor if it does not converge" are wrong. Yes, wrong. Very wrong.
> Completely wrong. Always wrong. To understand more please read Journal
> of Chemical Theory and Computation 9 (2013) 2786.
>
> b) Use MSR1, and in extreme cases perhaps MSEC3. Do not use BROYD.
> Perhaps reduce the greed to 0.1, almost never less than this.
>
> A little explanation. The factor of "0.005" is called the mixing
> greed.in the spirit of algorithm greed (e.g.
> http://en.wikipedia.org/wiki/Greedy_algorithm). If it is too large the
> self-consistent iterations can become unstable. However, you rarely
> need to deal with this and the mixer does. If you set it too a small
> value (which you did) you are making the algorithm take such tiny
> steps that it can starve to death. The code "honors" the user setting
> of a very small value (at least in 12.1) under the assumption that the
> user knows what he/she is doing.
>
> On Thu, Apr 24, 2014 at 5:25 AM, Martin Gmitra <martin.gmitra at gmail.com>
> wrote:
> > Dear Wien2k users,
> >
> > I am doing calculations of a hexaboride films invoking: runsp_c_lapw -so
> > -eece
> > My problem is two fold:
> >
> > (i) SCF calculations successfully converged for thin films (9 atomic
> units)
> > and bulk systems. I do have a problem to converge a thicker film (11
> atomic
> > units) even TEMP broadening of 0.02 is used. The observations after 800
> > iterations are following:
> >
> > (1) fermi energy is jumping (roughly) between two values
> > :FER  : F E R M I - ENERGY(FERMI-SM.)=   0.3682855520
> > :FER  : F E R M I - ENERGY(FERMI-SM.)=   0.3682855520
> > :FER  : F E R M I - ENERGY(FERMI-SM.)=  -0.7779431003
> > :FER  : F E R M I - ENERGY(FERMI-SM.)=  -0.7779431003
> > :FER  : F E R M I - ENERGY(FERMI-SM.)=   0.3683943150
> > :FER  : F E R M I - ENERGY(FERMI-SM.)=   0.3683943150
> > :FER  : F E R M I - ENERGY(FERMI-SM.)=  -0.7767634505
> > :FER  : F E R M I - ENERGY(FERMI-SM.)=  -0.7767634505
> >
> > (2) charge distance non uniformly oscillates between 0.1 and 0.001
> > :DIS  :  CHARGE DISTANCE       ( 1.1067771 for atom    4 spin 1)
> > 0.1064425
> > :DIS  :  CHARGE DISTANCE       ( 0.0059078 for atom    6 spin 1)
> > 0.0013328
> > :DIS  :  CHARGE DISTANCE       ( 0.0092322 for atom    6 spin 1)
> > 0.0015769
> > :DIS  :  CHARGE DISTANCE       ( 0.0092664 for atom    6 spin 1)
> > 0.0015106
> > :DIS  :  CHARGE DISTANCE       ( 0.5478509 for atom    4 spin 1)
> > 0.0466613
> > :DIS  :  CHARGE DISTANCE       ( 0.0078766 for atom    6 spin 1)
> > 0.0014700
> > :DIS  :  CHARGE DISTANCE       ( 0.9814094 for atom    4 spin 1)
> > 0.0939173
> > :DIS  :  CHARGE DISTANCE       ( 0.0070829 for atom    6 spin 1)
> > 0.0015672
> > :DIS  :  CHARGE DISTANCE       ( 0.0411319 for atom    4 spin 2)
> > 0.0053433
> > :DIS  :  CHARGE DISTANCE       ( 0.0072009 for atom    6 spin 1)
> > 0.0014308
> > :DIS  :  CHARGE DISTANCE       ( 0.1357701 for atom    4 spin 2)
> > 0.0150618
> >
> > (3) magnetic moments are zero within spheres whereas there is
> > :MMTOT: SPIN MAGNETIC MOMENT IN CELL   =    -0.00010
> > :MMINT: MAGNETIC MOMENT IN INTERSTITIAL =   -0.00003
> >
> > (4) my case.inm
> > BROYD  0.0   YES  (BROYD/PRATT, extra charge (+1 for additional e), norm)
> > 0.005           mixing FACTOR for BROYD/PRATT scheme
> > 1.00  1.00      PW and CLM-scaling factors
> > 9999  8         idum, HISTORY
> >
> > :MIX  :   MSEC3  REGULARIZATION: 2.50E-04  GREED: 0.005  Newton 1.000
> > with PRATT after 100 iterations
> > MIX  :   PRATT  REGULARIZATION: 2.50E-04  GREED: 0.005
> >
> > Do you have any hints how to converge the calculations?
> >
> > (ii) I am running the calculations with version 12.1. The runsp_c_lapw
> > script has been updated (debugged) in version 13.1 but SCF diverges in my
> > cases (thin and thicker films).
> >
> > Does anybody experience similar problem?
> >
> > Best regards,
> > Martin Gmitra
> > Uni Regensburg
> >
> >
> >
>
>
>
> --
> Professor Laurence Marks
> Department of Materials Science and Engineering
> Northwestern University
> www.numis.northwestern.edu 1-847-491-3996
> "Research is to see what everybody else has seen, and to think what
> nobody else has thought"
> Albert Szent-Gyorgi
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