Dear Aiyad ! Try reducing "mixing_beta"(make it ~ 0.2 to 0.5) and your "ecutwfc" is too large.. I think 40-50 Ryd will suffice. Since you are using ultrasoft pseudopotential your ecutrho should be atleast 8 times the ecutwfc. And the value of the convergence threshold that you have set is too low. Make it to ~1.E-08..Try the suggestions, may be you will get rid of the convergence problem.
On Mon, Nov 21, 2011 at 11:27 PM, IYAD AL-QASIR <iyad.ne at gmail.com> wrote: > Hello All, > I am trying to calculate the phonon dispersion relations and phonon > density of states of UO2. > Please find the attached files UO2.scf.in and UO2.ph.in > > The calculations assume GGA and include spin-polarized effects. > > There are 6 representations and nine modes. The problem I have is: When I > run the input file UO2.ph.in, the second representation of the second > mode for q (-0.1666667 0.1666667 -0.1666667), the *scf **calculations > do not converge.* > > Notes: > 1- My runs assume UO2 is metallic, in fact UO2 is insulator with band gap > of 2eV.( However, when I do the calculations using the VASP code I got very > good result only by including the polarization effects) > 2- In order to account for the band gap, one should implement the Hubbard > term (LDA/GGA+U) > 3- I tried different occupations (smearing, tetrahedra) > 4- I tried different starting_magnetization= 0.5, 1.0 > 5- the lattice parameter a= 10.285, is based on optimizing the structure > and including spin-polarization effects. > > > Any adivce to overcome this problem is highly welcomed. > > Kindest Regards, > ______________________________ > aIYAD I. AL-QASIR, PhD > Research Associate > > Department of Nuclear Engineering > North Carolina State University > Campus Box 7909 > 2500 Stinson Dr. > Raleigh, NC 27695-7909 > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- Regards, MOHNISH, ----------------------------------------------------------------- Mohnish Pandey BTech-Mtech, IIT Kanpur Senior Project Associate, Department of Chemical Engineering, IIT KANPUR, UP, INDIA ----------------------------------------------------------------- -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20111122/585531c3/attachment.htm
