<div dir="auto">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.<br><br><div data-smartmail="gmail_signature">---<br>Professor Laurence Marks<br>"Research is to see what everybody else has seen, and to think what nobody else has thought", Albert Szent-Gyorgi<br><a href="http://www.numis.northwestern.edu">http://www.numis.northwestern.edu</a><br>Corrosion in 4D <a href="http://MURI4D.numis.northwestern.edu">http://MURI4D.numis.northwestern.edu</a><br>Partner of the CFW 100% gender equity project, <a href="http://www.cfw.org/100-percent">www.cfw.org/100-percent</a><br>Co-Editor, Acta Cryst A<br> </div></div><div class="gmail_extra"><br><div class="gmail_quote">On Jan 26, 2017 07:28, "Laurence Marks" <<a href="mailto:L-marks@northwestern.edu">L-marks@northwestern.edu</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="auto"><div>The last two (three) have useful information. They are<div dir="auto"><br></div><div dir="auto">Mode Size Step</div><div dir="auto"><br></div><div dir="auto">Mode is whether the trust region is active; it is off when Newton is shown.</div><div dir="auto"><br></div><div dir="auto">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.</div><div dir="auto"><br></div><div dir="auto">Step is the magnitude of the step taken compared to a full Pratt step.</div><div dir="auto"><br></div><div dir="auto">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.)</div><div dir="auto"><br></div><div dir="auto">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.<br><br><div data-smartmail="gmail_signature" dir="auto">---<br>Professor Laurence Marks<br>"Research is to see what everybody else has seen, and to think what nobody else has thought", Albert Szent-Gyorgi<br><a href="http://www.numis.northwestern.edu" target="_blank">http://www.numis.northwestern.<wbr>edu</a><br>Corrosion in 4D <a href="http://MURI4D.numis.northwestern.edu" target="_blank">http://MURI4D.numis.<wbr>northwestern.edu</a><br>Partner of the CFW 100% gender equity project, <a href="http://www.cfw.org/100-percent" target="_blank">www.cfw.org/100-percent</a><br>Co-Editor, Acta Cryst A<br> </div></div><br><div class="gmail_extra"><br><div class="gmail_quote">On Jan 26, 2017 05:02, "Luis Ogando" <<a href="mailto:lcodacal@gmail.com" target="_blank">lcodacal@gmail.com</a>> wrote:<br type="attribution"><blockquote class="m_-164272534324926755quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div>Dear Prof. Marks,<br>
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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<br>
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:MIX : MSE1 REGULARIZATION: 6.30E-06 GREED: 0.317 Newton 1.00 0.22<br>
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:MIX : MSE1 REGULARIZATION: 4.93E-06 GREED: 0.437 Newton 1.00 1.14<br>
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Thank you once more !<br>
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* PS: Could you, please, clarify the meaning of the last two columns in the :MIX line ?
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<div>Dear Prof. Marks,<br>
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Thank you very much for your answers ! I am pretty sure that your "intuition" will save a lot of computation time !<br>
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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.<br>
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<wbr> 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.<br>
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<wbr> My question is : in this case (regular SCF cycle and InP cells), would you change any of your previous answers ?<br>
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Thank you again !!<br>
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All the best,<br>
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Luis<br>
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<div class="m_-164272534324926755m_-1386892226711550857h5">2017-01-25 17:56 GMT-02:00 Laurence Marks <span dir="ltr"><<a href="mailto:L-marks@northwestern.edu" target="_blank">L-marks@northwestern.edu</a>></span>:<br>
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<<a href="mailto:lcodacal@gmail.com" target="_blank">lcodacal@gmail.com</a>></span> wrote:<br>
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<div>Dear Prof. Marks (and Wien2k community),<br>
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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.<br>
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I have a system with:<br>
* 5 rings with C, H and N atoms<br>
* 100 atoms with P1 symmetry <br>
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1) Do you believe that MSEC3a will work better than MSR1a in such a case ?<br>
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<div>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.</div>
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2) Do you recommend using -it, -vec2pratt and -noHinv options with run_lapw ?<br>
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<div>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
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3) Should I reduce TRUST to 0.5 (I am using LDA and experimental values for the initial atomic positions) ?<br>
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<div>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. </div>
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4) Should I use SLOW in case.inm ? <br>
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<div>See my answer to 1) </div>
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Many thanks in advance.<br>
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All the best,<br>
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Luis<br>
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<div dir="ltr"><span style="font-size:12.8px">Professor Laurence Marks</span><br>
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<div dir="ltr"><span style="font-size:12.8px">"Research is to see what everybody else has seen, and to think what nobody else has thought", </span><span style="font-size:12.8px">Albert Szent-Gyorgi</span><br>
<a href="http://www.numis.northwestern.edu" target="_blank">www.numis.northwestern.edu</a> ; <span style="font-size:12.8px">C<wbr>orrosion in 4D:
</span><a href="http://MURI4D.numis.northwestern.edu" style="font-size:12.8px" target="_blank">MURI4D.numis.northwestern.edu</a>
<div><span style="font-size:12.8px">Partner of the CFW 100% program for gender equity, </span><a href="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=" style="font-size:12.8px" target="_blank">www.cfw.org/100-percen<wbr>t</a></div>
<div>Co-Editor, Acta Cryst A</div>
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