Dear Profs. Blaha and Marks, Thanks for your answer, I really appreciated it: taught me a few differences between LAPW and pseudopotential calculations. The calculation actually converged after a few more iterations. It looks like the first inclusion of U is the most problematic - I started from U=1 eV and increased it to 4 eV in steps of 1 eV, and the subsequent runs took quite fewer steps to converge.
Thanks very much, Marcos Universidad de Cantabria, Spain On Mon, Apr 25, 2011 at 9:34 PM, Laurence Marks <L-marks at northwestern.edu>wrote: > As Peter said, do NOT simply reduce the greed, it does not work the > same as it does in PP calculations. > > More to the point, you/we need more information to know what is going > on. Assuming that you are using the latest version (or similar) then > > grep -e :DIR -e GREED -e :FRMS -e :ENE -e :CHARG -e PRATT -e :DIS -e > "MIXING SC" -e PLANE *.scf | tail -40 > > will give more information and what is really going on... > > On Mon, Apr 25, 2011 at 2:21 PM, Peter Blaha > <pblaha at theochem.tuwien.ac.at> wrote: > > The convergence behaviour is not very good, but it is not too bad either. > > > > Check also :MMT or some :MMI0xx > > > > For more complicated cases (metallic ??) it is well possible that one > needs > > more > > than 40 iterations. Thus my suggestion is to keep going and submit > another > > job. > > > > Sometimes it is better to keep the history (use -NI switch), sometimes it > > can also > > be better to remove the history (rm *.broy*; which will be done > > automatically when > > -NI is not supplied). > > > > The mixing parameter has little importance with MSEC1, but still, a too > > small mixing > > can lead to too small steps and thus "pseudoconvergence" (this simply > means, > > that so > > little new density is mixed, that eg. the total energy is not changing > and > > one thinks > > the calculation is converged). > > > > PRATT is most likely "useless" for your problem. > > > > In LDA+U calculations it is easily possible to reach different states > > (different > > orbital occupations), which are stable and local minima. Once you have > > reached > > convergence, there is never a guarantee that this is the groundstate and > > really > > has the lowest energy. > > The suggested procedure in the UG is NOT ALWAYS leading to the lowest > state, > > but often it will do. > > > > > >> I have searched the list but I'm a bit confused with the posts, so I'll > >> pose my questions here. > >> > >> I am running LDA+U with and without spin-orbit coupling for a structure > in > >> a cell with the following cell parameters (Bohr): > >> > >> P LATTICE,NONEQUIV.ATOMS: 14127_P4/mbm > >> MODE OF CALC=RELA > >> 10.353171 10.353171 43.972470 90.000000 90.000000 90.000000 > >> > >> and a cell sampling of 12x12x3, which gives 432 points in the BZ, 42 in > >> the IBZ. My RKMAX is 8 - it was necessary to go to such high values to > >> converge the spin moment of > >> the system, as well as the energy down to 1 mRy. I followed the > procedure > >> stated in the manual: started with the LSDA calculation, then included > >> spin-orbit coupling and now > >> I am including the U gradually (well, at this point, just trying to...). > I > >> have to get to U=4 eV, so I'm growing it in steps of 1 eV. > >> > >> Convergence was very good for the LSDA+U calculations without SOC, and > >> they have finished, already (that is, I have already gotten to the 4 eV > in > >> U). However, I am having > >> problems converging the scf, with the charge and energy distances (as > >> obtained by grep convergence case.dayfile) oscillating, and never > attaining > >> convergence, which I set > >> to ec=0.00001 and cc=0.0001 (the numbers are appended by the end of this > >> message). More than 40 SCF steps have passed. > >> > >> Usually, in pseudopotential calculations, one possible solution is to > >> decrease the mixing weight of the charge densities for the following SCF > >> step, and the other is to > >> increase the smearing temperature. I would like to tweak with the mixing > >> rather than increasing the temperature, if possible, because from my > >> experience, increasing the > >> temperature can sometimes lead to a non-magnetic state. However, I see > >> from the mailing list that (at least in LAPW calculations), too small a > >> mixing can lead to > >> pseudo-convergence - which I don't understand what is. So, my questions > >> are the following: > >> > >> 1) What is the best thing to do to make my calculation converge: > increase > >> the mixing, or to diminish it? Should I change the mixing for MSEC1, and > if > >> so, by which amount? > >> Or, would it be good to change to PRATT, instead? I am quite lost with > >> regards to that. > >> 2) Would the application of SOC to the already converged LSDA+U > >> calculation yield too different results from starting from a converged > >> LSDA+SOC with later inclusion of U? > >> 3) What is the pseudo-convergence mentioned in previous emails in the > >> list? > >> > >> Of course, I will gladly provide more information, if needed. > >> > >> Best regards, > >> > >> Marcos > >> Universidad de Cantabria, Spain > >> > >> ======================================= > >> > >> Convergence of energy and charge distances: > >> > >> :ENERGY convergence: 0 0.00001 .0002941150000000 > >> :CHARGE convergence: 0 0.0001 .0088826 > >> :ENERGY convergence: 0 0.00001 .0000916950000000 > >> :CHARGE convergence: 0 0.0001 .0085946 > >> :ENERGY convergence: 0 0.00001 .0000428400000000 > >> :CHARGE convergence: 0 0.0001 .0112915 > >> :ENERGY convergence: 0 0.00001 .0001772500000000 > >> :CHARGE convergence: 0 0.0001 .0113780 > >> :ENERGY convergence: 0 0.00001 .0002456850000000 > >> :CHARGE convergence: 0 0.0001 .0104415 > >> :ENERGY convergence: 0 0.00001 .0001420300000000 > >> :CHARGE convergence: 0 0.0001 .0083852 > >> :ENERGY convergence: 0 0.00001 .0000500150000000 > >> :CHARGE convergence: 0 0.0001 .0084675 > >> :ENERGY convergence: 0 0.00001 .0001809700000000 > >> :CHARGE convergence: 0 0.0001 .0134776 > >> :ENERGY convergence: 0 0.00001 .0001993400000000 > >> :CHARGE convergence: 0 0.0001 .0112308 > >> :ENERGY convergence: 0 0.00001 .0002392700000000 > >> :CHARGE convergence: 0 0.0001 .0104208 > >> :ENERGY convergence: 0 0.00001 .0002088150000000 > >> :CHARGE convergence: 0 0.0001 .0069138 > >> :ENERGY convergence: 0 0.00001 .0001630050000000 > >> :CHARGE convergence: 0 0.0001 .0109876 > >> :ENERGY convergence: 0 0.00001 .0002176700000000 > >> :CHARGE convergence: 0 0.0001 .0012609 > >> :ENERGY convergence: 0 0.00001 .0001806300000000 > >> :CHARGE convergence: 0 0.0001 .0042825 > >> :ENERGY convergence: 0 0.00001 .0000720450000000 > >> :CHARGE convergence: 0 0.0001 .0045301 > >> :ENERGY convergence: 0 0.00001 .0000129050000000 > >> :CHARGE convergence: 0 0.0001 .0011304 > >> :ENERGY convergence: 0 0.00001 .0002283150000000 > >> :CHARGE convergence: 0 0.0001 .0047456 > >> :ENERGY convergence: 0 0.00001 .0003098100000000 > >> :CHARGE convergence: 0 0.0001 .0100820 > >> :ENERGY convergence: 0 0.00001 .0003708750000000 > >> :CHARGE convergence: 0 0.0001 .0087276 > >> :ENERGY convergence: 0 0.00001 .0000788950000000 > >> :CHARGE convergence: 0 0.0001 .0090876 > >> :ENERGY convergence: 0 0.00001 .0000849050000000 > >> :CHARGE convergence: 0 0.0001 .0093747 > >> :ENERGY convergence: 0 0.00001 .0000842350000000 > >> :CHARGE convergence: 0 0.0001 .0079561 > >> :ENERGY convergence: 0 0.00001 .0000553500000000 > >> :CHARGE convergence: 0 0.0001 .0122027 > >> :ENERGY convergence: 0 0.00001 .0000434050000000 > >> :CHARGE convergence: 0 0.0001 .0109352 > >> :ENERGY convergence: 0 0.00001 .0000227750000000 > >> :CHARGE convergence: 0 0.0001 .0122136 > >> :ENERGY convergence: 0 0.00001 .0000194300000000 > >> :CHARGE convergence: 0 0.0001 .0121261 > >> :ENERGY convergence: 0 0.00001 .0000292700000000 > >> :CHARGE convergence: 0 0.0001 .0131197 > >> :ENERGY convergence: 0 0.00001 .0000360650000000 > >> :CHARGE convergence: 0 0.0001 .0110031 > >> :ENERGY convergence: 0 0.00001 .0000300950000000 > >> :CHARGE convergence: 0 0.0001 .0115123 > >> :ENERGY convergence: 0 0.00001 .0000323600000000 > >> :CHARGE convergence: 0 0.0001 .0099887 > >> :ENERGY convergence: 0 0.00001 .0000147550000000 > >> :CHARGE convergence: 0 0.0001 .0110331 > >> :ENERGY convergence: 0 0.00001 .0001196200000000 > >> :CHARGE convergence: 0 0.0001 .0005253 > >> > >> > >> > >> _______________________________________________ > >> Wien mailing list > >> Wien at zeus.theochem.tuwien.ac.at > >> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > > > > -- > > ----------------------------------------- > > Peter Blaha > > Inst. Materials Chemistry, TU Vienna > > Getreidemarkt 9, A-1060 Vienna, Austria > > Tel: +43-1-5880115671 > > Fax: +43-1-5880115698 > > email: pblaha at theochem.tuwien.ac.at > > ----------------------------------------- > > _______________________________________________ > > Wien mailing list > > Wien at zeus.theochem.tuwien.ac.at > > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > > > > > > -- > Laurence Marks > Department of Materials Science and Engineering > MSE Rm 2036 Cook Hall > 2220 N Campus Drive > Northwestern University > Evanston, IL 60208, USA > Tel: (847) 491-3996 Fax: (847) 491-7820 > email: L-marks at northwestern dot edu > Web: www.numis.northwestern.edu > Chair, Commission on Electron Crystallography of IUCR > www.numis.northwestern.edu/ > Research is to see what everybody else has seen, and to think what > nobody else has thought > Albert Szent-Gyorgi > _______________________________________________ > Wien mailing list > Wien at zeus.theochem.tuwien.ac.at > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > -------------- next part -------------- An HTML attachment was scrubbed... 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