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 > Co-Editor, Acta Cryst A > > _______________________________________________ > 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 > >
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