Dear Blaha, Thank you. Then i can find the minimum energy structure with low RKMAX. After that using minimum energy structure lattice parameter with actual RKMAX, i have to run SCF and mini. am i correct?
Peter Blaha <pblaha at theochem.tuwien.ac.at> wrote: Yes, but you would NEVER do the whole optimization with this large parameter, only at the very end you switch to it. Santhy Jaiker schrieb: > Dear Blaha, > Thanks for your reply. > I want to find the enthalpy of formation of Fe2Ti. I know that RKMAX=10 > is high for Fe2Ti. I thought that higher RKMAX will increase the > accuracy and computation time. I have chosen convergence criteria for > RKAMX is <5mev/atom (~0.0003Ry/atom). For Fe in BCC and Ti in HCP, > satisfies this condition when RKMAX is 10. So highest RKMAX should be > used to find out the energy of the elements and compound. That?s why I > used RKMAX=10. > Am I correct? > > > */Peter Blaha /* wrote: > > Certainly the message: > mini.error (stop in mini forces small) > is NOT an error, but leads to a stop because the optimization has > finished properly. > > The > lapw1.error (Cholesky INFO = 2198 'SECLR4' - POTRF > (scalarpack/lapack) failed) > is a "real" error. Often it comes because your structure is wrong > (sometimes the > optimization may break symmetry (move atoms in a symmetry breaking > way!). > > Otherwise, your RKMAX=10 may be too large. > Why would you do it that way ? > > Start with the default (RKMAX=7). It is probably 100 times !!!! faster. > Anc once you have the minimum with RKMAX=7; you continue with > RKMAX=8 and > check if the minimum has changed. If not, you are done. > > Santhy Jaiker schrieb: > > I am trying to optimize Fe2Ti system for more than a month. Still > i am > > facing problem in it. > > > > Structure Details: Positions of atoms Fe (0,0,0) and > (0.1705,0.341,1/4) > > Ti (1/3,2/3,0.5647) > > a=b=4.794 A c=7.834 A > > alpha=beta=90 degree gamma=120 degree > > Parameters: RMT (of Fe and Ti) =2 k point =76 IBZ Gmax=14 > > mixer=0.20 RKmax=10 > > > > Force are there in atom 2 and atom 3 > > > > SCF and mini calculation runs nicely. > > During optimization with mini, varying volume from -5 to 0%, it > > shows error in > > -3% volume reduction. It shows mini.error (stop in mini forces small) > > > > Since i tried optimization without mini, it runs nicely from -5 > to 0% > > volume reduction. But it shows error in c/a ratio optimization. Both > > mini.error (stop in mini forces small) and lapw1.error (Cholesky > INFO = > > 2198 'SECLR4' - POTRF (scalarpack/lapack) failed). > > > > I know that i am doing mistake some where. Because of that i > tried all > > the possiblities. But i am not able to trace it out. Any suggestions > > regarding this problem will be helpful. > > > > Thanks in advance > > > > > > Regards, > > Santhy Jaiker > > > > Research Scholar, > > Materials Thermodynamics Lab, > > Department of Metallurgical and Materials Engineering, > > Indian Institute of Technology Madras, > > Chennai - 600 036, India > > Tel: 91-044-22575763 > > ********************************************** > > A truly happy person is one > > who can enjoy the scenery on a detour > > ********************************************** > > > > > ------------------------------------------------------------------------ > > Explore your hobbies and interests. Click here to begin. > > > > > > > > > > > ------------------------------------------------------------------------ > > > > _______________________________________________ > > Wien mailing list > > Wien at zeus.theochem.tuwien.ac.at > > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > > -- > > P.Blaha > -------------------------------------------------------------------------- > Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna > Phone: +43-1-58801-15671 FAX: +43-1-58801-15698 > Email: blaha at theochem.tuwien.ac.at WWW: > http://info.tuwien.ac.at/theochem/ > -------------------------------------------------------------------------- > _______________________________________________ > Wien mailing list > Wien at zeus.theochem.tuwien.ac.at > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > > > > > Regards, > Santhy Jaiker > > Research Scholar, > Materials Thermodynamics Lab, > Department of Metallurgical and Materials Engineering, > Indian Institute of Technology Madras, > Chennai - 600 036, India > Tel: 91-044-22575763 > ********************************************** > A truly happy person is one > who can enjoy the scenery on a detour > ********************************************** > > ------------------------------------------------------------------------ > Bollywood, fun, friendship, sports and more. You name it, we have it. > > > > > ------------------------------------------------------------------------ > > _______________________________________________ > Wien mailing list > Wien at zeus.theochem.tuwien.ac.at > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien -- P.Blaha -------------------------------------------------------------------------- Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna Phone: +43-1-58801-15671 FAX: +43-1-58801-15698 Email: blaha at theochem.tuwien.ac.at WWW: http://info.tuwien.ac.at/theochem/ -------------------------------------------------------------------------- _______________________________________________ Wien mailing list Wien at zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien Regards, Santhy Jaiker Research Scholar, Materials Thermodynamics Lab, Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai - 600 036, India Tel: 91-044-22575763 ********************************************** A truly happy person is one who can enjoy the scenery on a detour ********************************************** --------------------------------- From Chandigarh to Chennai - find friends all over India. Click here. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20080410/ac6625cb/attachment.html
