When doing structure minimization, I need to calculate a series of structures. Is it fine to set different Muffin-Tin sphere for different calculations. I believe it is fine because I am not comparing them with each other. Is it?
Yundi On Thu, Sep 1, 2011 at 12:41 PM, Laurence Marks <L-marks at northwestern.edu>wrote: > Yes, much to large. > > Read the FAQ on minimization, you are doing something wrong. > > 2011/9/1 Yundi Quan <quanyundi at gmail.com>: > > Thanks for you reply. My minimization stops with a message saying that > the > > force is minimized and the force and energy are inconsistent. So I > carried > > out another calculation by using the structure file that I got. However, > the > > force on one of the atoms is as large as 26. Is it too large to be used > as a > > equilibrium state? > > Thanks a lot. > > Yundi > > > > 2011/8/31 ??????? ???????? <evgeniya at theochem.tuwien.ac.at> > >> > >> I mean minimization of internal parameters (lattice coordinates) in your > >> initial structure. This is a crucial point. You should not have forces > on > >> atoms, since it is a kind of reference state. The structure optimization > >> (lattice parameters) itself is less crucial as long as you have the > >> reasonable lattice parameters. > >> > >> Once you have a well relaxed structure, you can construct atomic > >> displacements and calculate 'total forces' using force convergence > criteria > >> (-fc) at fixed lattice constants. > >> > >> Total forces, which you need for phonon calculations, are the > derivatives > >> of total energies with respect to atomic displacements. Therefore, in > order > >> to get more precise values of total forces one usually constructs big > >> supercells. This means that a size of your supercell is also important. > > > > > >> > >> > >> > >> 2011/8/31 Yundi Quan <quanyundi at gmail.com> > >>> > >>> By relaxing structure, do you mean internal structure or the crystal > >>> structure or both? > >>> > >>> Yundi > >>> > >>> 2011/8/31 ??????? ???????? <evgeniya at theochem.tuwien.ac.at> > >>>> > >>>> Fisrt you have to relax your structure until you have no forces on all > >>>> your atoms. Then you create the displacements and perform scf > calculations > >>>> without minimization. > >>>> > >>>> 2011/8/31 Yundi Quan <quanyundi at gmail.com> > >>>>> > >>>>> Hi, When doing phonon calculation, do I have to do structure > >>>>> minimization first? > >>>>> Yundi > >>>>> _______________________________________________ > >>>>> Wien mailing list > >>>>> Wien at zeus.theochem.tuwien.ac.at > >>>>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > >>>>> > >>>> > >>>> > >>>> > >>>> -- > >>>> Evgeniya Kabliman. > >>>> Insitute of Materials Chemistry Vienna University of > Technology > >>>> Getreidemarkt 9/165-TC, A-1060 Vienna, Austria > >>>> Tel: +43 1 58801 15674 Fax: +43 1 58801 15698 > >>>> evgeniya at theochem.tuwien.ac.at http://www.imc.tuwien.ac.at > >>>> > >>>> _______________________________________________ > >>>> Wien mailing list > >>>> Wien at zeus.theochem.tuwien.ac.at > >>>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > >>>> > >>> > >>> > >>> _______________________________________________ > >>> Wien mailing list > >>> Wien at zeus.theochem.tuwien.ac.at > >>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > >>> > >> > >> > >> > >> -- > >> Evgeniya Kabliman. > >> Insitute of Materials Chemistry Vienna University of Technology > >> Getreidemarkt 9/165-TC, A-1060 Vienna, Austria > >> Tel: +43 1 58801 15674 Fax: +43 1 58801 15698 > >> evgeniya at theochem.tuwien.ac.at http://www.imc.tuwien.ac.at > >> > >> _______________________________________________ > >> Wien mailing list > >> Wien at zeus.theochem.tuwien.ac.at > >> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > >> > > > > > > _______________________________________________ > > 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 > 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... URL: <http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20110901/bcf4dc65/attachment.htm>
