I have a structure that I supposed was well relaxed; Total force = 0.000624 and P= -0.00. But I still get negative frequencies.
Isn't such Forec/pressure good enough? Comments shall be appreciated. Isaiah On Sat, Jul 22, 2017 at 11:24 AM, Arles V. Gil Rebaza <[email protected]> wrote: > Dear Mohammad, try to relax your system using "relax" or "vc-relax" in > order to reduce the interatomic forces. After that use "scf" calculation > > Furthermore, &cell and &ions parts and forc_conv_thr tag does not work > for scf calculations. Please read the QE manual. > > Best > > Dr. Arles V. Gil Rebaza > IFLP - Argentina > > > El sábado, 22 de julio de 2017, Mohammad Alidoosti <[email protected]> > escribió: > >> >> Dear PWSCF users, >> >> I am doing phonon frequencies calculations for Graphene-oxide. In >> proximity to the Gamma point, I get small negative frequencies. As far as I >> know this is a known problem, I have tried to increase "forc_conv_thr" and >> "tr2_ph" to 1.0d-6 and 1.0d-16, respectively, but it doesn't work. Is there >> any suggestion for solving this problem? >> Hear is the scf input file : >> ********************************************************************* >> &control >> title = GO >> calculation = 'scf' >> restart_mode = 'from_scratch' >> prefix = 'GO-ph' >> pseudo_dir = '/home/pseudo' >> outdir = './tmp/' >> nstep = 200 , >> tstress = .true. , >> tprnfor = .true. , >> verbosity='high', >> forc_conv_thr= 1.0d-6 >> / >> &system >> ibrav = 0 >> nat = 12 >> ntyp = 3 >> ecutwfc = 80 >> ecutrho = 400 >> occupations = 'smearing' >> smearing='methfessel-paxton', >> degauss = 0.001 >> / >> &electrons >> conv_thr= 1.0d-8 >> mixing_beta = 0.7 >> electron_maxstep = 200, >> / >> &IONS >> / >> &CELL >> cell_dofree = '2Dxy', >> / >> ATOMIC_SPECIES >> C 12.0107 C.pbe-n-kjpaw_psl.0.1.UPF >> O 15.999 O.pbe-n-kjpaw_psl.0.1.UPF >> H 1.008 H.pbe-kjpaw_psl.0.1.UPF >> CELL_PARAMETERS (angstrom) >> 4.990235060 0.054948389 0.000000000 >> -2.541880421 4.219875071 0.000000000 >> 0.000000000 0.000000000 25.000000000 >> >> ATOMIC_POSITIONS (angstrom) >> O -0.021826634 0.250928937 1.721705471 >> H 0.809321037 0.681392784 1.997855886 >> O -0.031523808 1.135550155 -1.892027240 >> H 0.808877574 0.723408478 -2.168118129 >> C 0.047350145 0.017290716 0.288486347 >> C 0.032454255 1.370630042 -0.458840404 >> C -1.237500438 2.119007372 -0.142173618 >> C -1.224236423 3.485316018 -0.033121650 >> C 1.242549808 3.515955831 -0.028144886 >> C 1.285890831 2.150271662 -0.137183942 >> C 2.528922921 1.430926894 -0.090219298 >> C 2.544546281 0.011979550 -0.080086702 >> K_POINTS automatic >> 15 15 1 0 0 0 >> ******************************************************************* >> >> Thanks in advance. >> >> Mohammad Alidoosti >> -- >> Institute for Research in Fundamental Sciences (IPM) >> School of Nano-Science >> Shahid Farbin Alley >> Shahid Lavasani st >> P.Code: 19538-33511 >> Tehran, Iran >> Tel: +98 21 2310 -3070 >> >> > > -- > ###---------> Arles V. <---------### > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum > -- Isaiah Abu Moses Graduate Student, Physics Department, University of Ibadan, Nigeria
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