Dear Mojtaba,
1) for ferroelectric perovskites, use PBEsol, preferably, or LDA as an xc functional 2) for the particular case of the Ba, Ti and O pseudos, use either those three elements from the PBESOL pslibrary 1.0 (use a cutoff of 45 Ry, dual of 8), from http://www.qe-forge.org/gf/project/pslibrary/frs/?action=FrsReleaseView&release_id=147 or the ultrasoft PBESOL GBRV library (use a cutoff of 40 Ry, dual of 8), http://www.physics.rutgers.edu/gbrv/ 3) make sure you use atomic+random as initialization for the wavefunctions Not sure if your problems are related, but fix 1+2+3 above before anything. nicola On 14/03/2015 17:35, Mojtaba Mirseraji wrote: > Dear All > > I am using WC pseudopotentials (THEOS, PSLibrary) for relaxing BaTiO3. > These potentials are so good for cubic structure but when I use it for > tetragonal structure of barium titanate with some errors !!!!! > such as "not converged eigenvalues" , "S matrix not positive definite" > , "fail to eigenvectors" and .....!!!!!!! > > I only changed force_conv_thr and etot_cov_thr=1.D-2 are without error !!!! > > I do not know how to do !!! > PLEASE, help me > > Thanks in advance > > Mojtaba Mirseraji > Ph.D. Candidate > Theoretical Condensed Matter Physics > Arak Univ. > I.R.IRAN > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum > -- ---------------------------------------------------------------------- Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum
