It is safe, although it may not be efficient to do this. I would recommend changing it to 0.2 and doing "echo 0.05 > .msec" to give the algorithm a slight push if it has stagnated.
N.B., in the case sent pure PRATT mixing was being used for some reason, so this won't matter. On Thu, Apr 24, 2014 at 9:25 AM, Luis Ogando <lcoda...@gmail.com> wrote: > 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-ma...@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.gmi...@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 >> _______________________________________________ >> Wien mailing list >> Wien@zeus.theochem.tuwien.ac.at >> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien >> SEARCH the MAILING-LIST at: >> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html > > -- 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 _______________________________________________ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html