Dear Axel, Thanks for your reply!
I will try to understand and spent sometime learning what you suggested me to do. Best regards and have a good day! Haibei On Mon, Sep 1, 2014 at 11:41 AM, Axel Kohlmeyer <akohlmey at gmail.com> wrote: > > On Sep 1, 2014 1:16 AM, "Haibei Huang" <haibeih at student.unimelb.edu.au> > wrote: > > > > Dear Axel, > > > > Thanks for your reply. > > > > The truth is that I was trying to diagonalize a matrix made of a serials > of Energies obtained by pw.x, while some of elements in the matrix is quite > small (e.g. 10^-7 or 10-^8). Thus, I would like to know how many digits I > could trust in Energies. Or at least I should keep the Energies and these > small elements in the same scale, say 10^-8. > > For that, you do _not_ need more digits for exactly the reason I gave you. > If you output more digits, you are just adding random numbers. Literally. > > > > > Please let me know if you or anyone know how to change the code showing > more digits in pw.x. > > Many people know (including me). But why should anybody tell you, if what > you want is a stupid thing? Have you talked about this with your adviser? > > In general, please spent a little time learning about the systematic > errors of DFT, the numerical precision of floating point numbers, the > accuracy of a self-consistent calculation and error propagation. > > You should quickly see the folly of your request. > > > Best regards > > Haibei > > > > > > On Sun, Aug 31, 2014 at 1:51 PM, Axel Kohlmeyer <akohlmey at gmail.com> > wrote: > >> > >> > >> On Aug 30, 2014 10:57 PM, "Haibei Huang" < > haibeih at student.unimelb.edu.au> wrote: > >> > > >> > Dear All, > >> > > >> > I am aware of that the QE will only show at most 8 digits after the > decimal point in the output file, while more digits are needed in my > calculation. > >> > > >> > Could any of you provide a way to increase the number digits after > the decimal point? > >> > >> What is the point of using more digits, when the error is larger? You > could just add random digits and have the same effect. > >> > >> > > >> > Thanks for your time! > >> > Looking forward to your reply! > >> > Regards > >> > Haibei > >> > > >> > > >> > _______________________________________________ > >> > Pw_forum mailing list > >> > Pw_forum at pwscf.org > >> > http://pwscf.org/mailman/listinfo/pw_forum > >> > >> > >> _______________________________________________ > >> Pw_forum mailing list > >> Pw_forum at pwscf.org > >> http://pwscf.org/mailman/listinfo/pw_forum > > > > > > > > _______________________________________________ > > Pw_forum mailing list > > Pw_forum at pwscf.org > > http://pwscf.org/mailman/listinfo/pw_forum > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20140901/c27a99f6/attachment.html
