Please provide input data (and pseudopotentials if not available somewhere)
P. On Mon, 2013-04-01 at 14:28 -0400, Eduardo Ariel Menendez Proupin wrote: > Dear colleagues, > > > I have found strange differences in results for the calculation of > pressure using pwscf in versions 4.3 and 5.0.N (N=1,2). We are > calculating wurtzite CdSe, using the following UPF files. > > PAW calculation > Cd 112.40000 Cd.pbe-dn-kjpaw_psl.0.2.UPF > Se 78.96000 Se.pbe-n-kjpaw_psl.0.2.UPF > > > > Ultrasoft PP calculation > Cd 112.40000 Cd.pbe-dn-rrkjus_psl.0.2.UPF > Se 78.96000 Se.pbe-n-rrkjus_psl.0.2.UPF > > > > > For the PAW calculations, the convergence of pressure with the density > cutoff (euctrho) shows jumps (see the attached figure paw-press.eps) > and no convergence in the case of version 5.0.N, while there is > convergence with version 4.3. For both versions the total energies are > the same. > > The jumps are associated with differences in the number of symmetry > operations detected. The message > > " (note: 6 additional sym.ops. were found but ignored > their fractional translations are incommensurate with FFT > grid)" > > is associated with higher pressures (33 kbar). Lower pressures ~ 26 > kbar) are found when the FFT grid is commensurate and all 12 sym. ops. > are used. > In the calculations with version 4.3 the pressures are somewhat lower, > but apparently convergent. Also, there are less symmetry operations > detected or used than for version 5.0.N. > > > > In the ultrasoft calculations, (see figure uspp-press), both versions > 4.3 and 5.0.N produce convergent pressures vs ecutrho, but the > pressures differ almost by 10 kbar. (The total energies are almost > equal, as expected). > > > > Thanks for any comment. > > > -- > Eduardo Menendez Proupin > Departamento de Fisica, Facultad de Ciencias, Universidad de Chile > URL: http://fisica.ciencias.uchile.cl/~emenendez > "Lograremos el anhelado desarrollo cuando sea la ciudadan?a, y no los > cient?ficos, la que pida m?s ciencia para Chile." J. Babul > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum
