In my opinion, the stricter the criterion, the more ecut and more K points sampling.
2009/9/2 Huiqun Zhou <hqzhou at nju.edu.cn> > Pablo, > > Usually, setting conv_thr = 1d-8 is sufficient, please make sure if you > need such strict convergence criterion. > > > Huiqun Zhou > @Earth Sciences, Nanjing University, China > > > ----- Original Message ----- > From: "Pablo Aguado" <paguado at gmail.com> > To: <pw_forum at pwscf.org> > Sent: Tuesday, September 01, 2009 6:38 PM > Subject: [Pw_forum] Relaxation doesn't converge > > > > Dear all, > > > > I'm doing some tests on the structural optimization with pw. I'm > > currently testing with the tetragonal structure of PbTiO3, using the > > following input: > > > > &control > > calculation = 'vc-relax' > > restart_mode = 'restart' > > pseudo_dir = '/****/espresso-4.1/pseudo/' > > outdir = '/***/tmp' > > forc_conv_thr = 1d-3 > > nstep = 50 > > / > > &system > > ibrav=6 > > celldm(1)=7.3699 > > celldm(3)=1.04 > > nat=5 > > ntyp=3 > > nbnd=28 > > ecutwfc=30.0 > > occupations = 'fixed' > > / > > &electrons > > conv_thr = 1d-12, > > mixing_beta=0.4, > > / > > &ions > > ion_dynamics = 'bfgs' > > bfgs_ndim = 5 > > / > > &cell > > cell_dynamics = 'damp-pr' > > press_conv_thr = 1.0d0 > > cell_dofree = 'z' > > / > > ATOMIC_SPECIES > > Pb 207.2 Pb.pz-d-van.UPF > > Ti 47.867 Ti.pz-sp-van_ak.UPF > > O 15.9994 O.pz-van_ak.UPF > > ATOMIC_POSITIONS crystal > > Pb 0.000 0.000 0.040 0 0 1 > > Ti 0.500 0.500 0.520 0 0 1 > > O 0.000 0.500 0.500 0 0 1 > > O 0.500 0.500 0.000 0 0 1 > > O 0.500 0.000 0.500 0 0 1 > > K_POINTS automatic > > 6 6 6 1 1 1 > > > > The relaxation is taking forever so I've checked the output and I've > > found several steps where everything seems to be converged (notice I'm > > only relaxing out-of-plane lattice vector) but the code keeps running. > > An example: > > > > - Energy difference = 4e-7 > > - Forces acting on atoms (Ry/au): > > > > atom 1 type 1 force = 0.00000000 0.00000000 0.00085679 > > atom 2 type 2 force = 0.00000000 0.00000000 -0.00001779 > > atom 3 type 3 force = 0.00000000 0.00000000 -0.00024617 > > atom 4 type 3 force = 0.00000000 0.00000000 -0.00034665 > > atom 5 type 3 force = 0.00000000 0.00000000 -0.00024617 > > > > Total force = 0.000988 Total SCF correction = 0.000002 > > > > total stress (Ry/bohr**3) (kbar) > > P= -0.84 > > -0.00001150 0.00000000 0.00000000 -1.69 0.00 0.00 > > 0.00000000 -0.00001150 0.00000000 0.00 -1.69 0.00 > > 0.00000000 0.00000000 0.00000591 0.00 0.00 0.87 > > > > Any idea of what's going on? > > > > Thank you very much > > > > Pablo > > _______________________________________________ > > Pw_forum mailing list > > Pw_forum at pwscf.org > > http://www.democritos.it/mailman/listinfo/pw_forum > > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > -- Y. C. Cheng Department of Physics Nanjing University Nanjing 210093 P. R. China Tel: 86-25-83592907 Email: yccheng.nju at gmail.com -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20090902/3bbdf3b9/attachment.htm
