N.B., the latest release has some additional controls that allow for a bit more control of the trust region, e.g. a maximum size. These are in the README, they are not in the user guide. They should only be used by experts for really nasty to converge problems.

--- Professor Laurence Marks "Research is to see what everybody else has seen, and to think what nobody else has thought", Albert Szent-Gyorgi http://www.numis.northwestern.edu Corrosion in 4D http://MURI4D.numis.northwestern.edu Partner of the CFW 100% gender equity project, www.cfw.org/100-percent Co-Editor, Acta Cryst A On Jan 26, 2017 07:28, "Laurence Marks" <l-ma...@northwestern.edu> wrote: > The last two (three) have useful information. They are > > Mode Size Step > > Mode is whether the trust region is active; it is off when Newton is shown. > > Size is the radius of the trust region compared to a full Newton step, for > instance 0.5 would mean only half the full radius. > > Step is the magnitude of the step taken compared to a full Pratt step. > > All mixer codes (other DFT as well) use a Taylor series expansion for the > density change with some approximation for the Jacobian (see the mixer > README & papers). MSEC3 & MSR1 use different Jacobian approximations, as > did the old BROYD. Neglecting the higher-order terms is only valid for some > total step magnitude, the trust-region radius which is the "Size" variable > above. When Size is small the algorithm thinks these higher-order terms > matter. (The mixer adjusts the trust-region radius depending upon how much > the self-consistency is improving, which is very tricky, fuzzy coding and > imperfect.) > > The numbers you sent indicate that the algorithm thinks everything is > "fine". If Size is small (e.g. 0.05) and remains small that suggests a > problem. The "Step" term can be small when :DIS is large, but should not be > small near the solution. If it is large (2-3 or more) the algorithm thinks > that there are soft modes present. > > --- > Professor Laurence Marks > "Research is to see what everybody else has seen, and to think what nobody > else has thought", Albert Szent-Gyorgi > http://www.numis.northwestern.edu > Corrosion in 4D http://MURI4D.numis.northwestern.edu > Partner of the CFW 100% gender equity project, www.cfw.org/100-percent > Co-Editor, Acta Cryst A > > > > On Jan 26, 2017 05:02, "Luis Ogando" <lcoda...@gmail.com> wrote: > > Dear Prof. Marks, > > Just for completeness, in the InP case I am using mBJ and I have > checked that during the last 20 regular SCF cycles the steps are changing > from > > :MIX : MSE1 REGULARIZATION: 6.30E-06 GREED: 0.317 Newton 1.00 0.22 > > to > > :MIX : MSE1 REGULARIZATION: 4.93E-06 GREED: 0.437 Newton 1.00 1.14 > > Thank you once more ! > All the best, > Luis > * PS: Could you, please, clarify the meaning of the last two columns in > the :MIX line ? > > 2017-01-26 8:18 GMT-02:00 Luis Ogando <lcoda...@gmail.com>: > >> Dear Prof. Marks, >> >> Thank you very much for your answers ! I am pretty sure that your >> "intuition" will save a lot of computation time ! >> Just one last question: I have another system , a supercell formed by >> 15 InP zinc blend cells along [111] (hexagonal representation of the cubic >> lattice) and 3 InP wurtzite cells. They are aligned along the hexagonal "c" >> axis. >> Comparing the gaps of the >> respective bulks and this supercell (same calculation parameters) , I >> believe that the SCF cycle (here, it is not a lattice optimization) stopped >> at a local minimum. >> My question is : in this case >> (regular SCF cycle and InP cells), would you change any of your previous >> answers ? >> Thank you again !! >> All the best, >> Luis >> >> >> 2017-01-25 17:56 GMT-02:00 Laurence Marks <l-ma...@northwestern.edu>: >> >>> Inlined is my intuition, which does not have to be completely right. >>> >>> On Wed, Jan 25, 2017 at 11:32 AM, Luis Ogando <lcoda...@gmail.com> >>> wrote: >>> >>>> Dear Prof. Marks (and Wien2k community), >>>> >>>> After a recent discussion about "difficult" optimizations in this >>>> mailing list (subject: "Mixer surprise when using PBE0 hybrid on-site >>>> functional"), I would like ask you for an advice. >>>> I have a system with: >>>> * 5 rings with C, H and N atoms >>>> * 100 atoms with P1 symmetry >>>> * the rings are out of a plane >>>> * vacuum along y and z >>>> I know that this is a very hard optimization problem, so I would >>>> like to kindly ask: >>>> >>>> 1) Do you believe that MSEC3a will work better than MSR1a in such a >>>> case ? >>>> >>> >>> I would switch to MSEC3a, use SLOW or reduce the GREED to 0.1 only if >>> you see indications of problems. If the system is a decent insulator and >>> the experimental positions are quite good you may have no problems. At the >>> end I would switch back to MSR1a certainly for a system with OH as the >>> positions of the hydrogens can be quite soft. It can take quite some time >>> to get the rotations of the OH bond distance right as Wien2k uses cartesian >>> coordinates not polars. Which of the 3 is best -- I am not sure. >>> >>>> >>>> 2) Do you recommend using -it, -vec2pratt and -noHinv options with >>>> run_lapw ? >>>> >>> >>> I use -it -noHinv -vec2pratt. Sometimes you need to do an occasional >>> full diagonalization (touch .fulldiag) as the iterative method is less >>> stable (it adds a little noise). In my personal version I have added back >>> the old -itn option so this is done automatically every few steps. >>> >>>> >>>> 3) Should I reduce TRUST to 0.5 (I am using LDA and experimental values >>>> for the initial atomic positions) ? >>>> >>> >>> Probably not. TRUST 0.5 would be if it is taking much too large steps >>> which tends (in my experience) to occur more with soft electronic modes >>> such as one has with d and f electrons. >>> >>>> >>>> 4) Should I use SLOW in case.inm ? >>>> >>> >>> See my answer to 1) >>> >>>> >>>> Many thanks in advance. >>>> All the best, >>>> Luis >>>> >>>> >>> >>> >>> -- >>> Professor Laurence Marks >>> "Research is to see what everybody else has seen, and to think what >>> nobody else has thought", Albert Szent-Gyorgi >>> www.numis.northwestern.edu ; Corrosion in 4D: >>> MURI4D.numis.northwestern.edu >>> Partner of the CFW 100% program for gender equity, >>> www.cfw.org/100-percent >>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.cfw.org_100-2Dpercent&d=CwMFaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=CZHTnM-OmVb7WVhK4QBSMqumiacPyU-LxrLt8-sw9bU&s=cyXhG2IW3LH9f7wuLmlZGAS47BrtGluAX3LnBa9-Mug&e=> >>> Co-Editor, Acta Cryst A >>> >>> _______________________________________________ >>> Wien mailing list >>> Wien@zeus.theochem.tuwien.ac.at >>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien >>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__zeus.theochem.tuwien.ac.at_mailman_listinfo_wien&d=CwMFaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=CZHTnM-OmVb7WVhK4QBSMqumiacPyU-LxrLt8-sw9bU&s=nujfSCNX55lo__i30MehzUrgntz21bjkJFguwZ82Uzs&e=> >>> SEARCH the MAILING-LIST at: http://www.mail-archive.com/wi >>> e...@zeus.theochem.tuwien.ac.at/index.html >>> <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mail-2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_index.html&d=CwMFaQ&c=yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=CZHTnM-OmVb7WVhK4QBSMqumiacPyU-LxrLt8-sw9bU&s=MJqLknQDobuUH-IAiKowy5gMln1IboZOxcaawJzfRUs&e=> >>> >>> >> > >

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