Dear Cheng, > ????conv_thr = 1.D-12, You wast time with this threshold. Use less strong criteria.
> ????????? -2.01782?????? > ????????? 2.04775??????? I would say the Born charges are equivalent (by absolut values) with a numerical noise. Within this noise charges' sum is zero. > ? tr2_ph=1.0d-12, Try d-14, and more ecutwfc. Bests, Eyvaz. ------------------------------------------------------------------- Prof. Eyvaz Isaev, Theoretical Physics Department, Moscow State Institute of Steel & Alloys, Russia, Department of Physics, Chemistry, and Biology (IFM), Linkoping University, Sweden Condensed Matter Theory Group, Uppsala University, Sweden Eyvaz.Isaev at fysik.uu.se, isaev at ifm.liu.se, eyvaz_isaev at yahoo.com --- On Mon, 6/29/09, ??? <yccheng.nju at gmail.com> wrote: > From: ??? <yccheng.nju at gmail.com> > Subject: [Pw_forum] the sum of the born effective charge in phonon calculation > To: "PWSCF Forum" <pw_forum at pwscf.org> > Date: Monday, June 29, 2009, 7:10 PM > Dear pwscf users, > ??? I calculated?the phonon?of ZnS at Gamma > point.? I checked the output file, and found that the sum > of the born effective charge is not zero. > ================================ > ????????? Effective charges E-U in cartesian > axis > ?????????? atom???? 1 > ????????? (?????? -2.01782??????? > 0.00000??????? 0.00000 ) > ????????? (??????? 0.00000?????? > -2.01782??????? 0.00000 ) > ????????? (??????? 0.00000??????? > 0.00000?????? -2.01782 ) > ?????????? atom???? 2 > > ????????? (??????? 2.04775??????? > 0.00000??????? 0.00000 ) > ????????? (??????? 0.00000??????? > 2.04775??????? 0.00000 ) > ????????? (??????? 0.00000??????? > 0.00000??????? 2.04775 ) > ================================ > > My question?: > 1.?why the sum of the effectvie charge is not > zero? > 2.how to improve the calculation of born effective > charge? > ? > The following is my input files: > scf.in > ?&CONTROL > ?????????????????????? title = fine, > ????????????????????? prefix = > 'zns' > ???????????????? calculation = > 'scf' , > ??????????????? restart_mode = > 'from_scratch' , > ????????????????? wf_collect = .false. , > > ????????????????????? outdir = > './' , > ????????????????? pseudo_dir = > './' , > ???????????????????? tstress = .true. > , > ???????????????????? tprnfor = .true. > , > ?????????????????????? nstep = 100 , > > ?/ > ?&SYSTEM > ?????????????????????? ibrav = 2, > ?????????????????? celldm(1) = > 10.204964632, > ???????????????????????? nat = 2, > ??????????????????????? ntyp = 2, > ???????????????????? ecutwfc = 80, > ?????????????????????? nosym = > .false. , > > ?/ > ?&ELECTRONS > ??????????? electron_maxstep = 100, > ??????????????????? conv_thr = 1.D-12, > ?/ > ATOMIC_SPECIES > ??? S?? 32.066?? 16-S.GGA.fhi.UPF > ??? Zn? 65.409?? 30-Zn.GGA.fhi.UPF > ATOMIC_POSITIONS crystal > > S??????? 0.250000000?? 0.250000000?? > 0.250000000 > Zn?????? 0.000000000?? 0.000000000?? 0.000000000 > K_POINTS automatic > ? 16 16 16 0 0 0 > > ph.in > phonon calculation for ZnS > &inputph > ? tr2_ph=1.0d-12, > ? prefix='zns', > ? epsil=.true., > ? trans=.true., > ? lraman=.true., > ? elop=.true., > ? amass(1)=32.066, > ? amass(2)=65.409, > ? outdir='./', > > ? fildyn='ZnS_IR.dynG', > ? fildrho='ZnS_IR.drho', > ?/ > 0.0 0.0 0.0 > > > -- > Y. C. Cheng > Department of Physics > Nanjing University > Nanjing 210093 > P. R. China > Tel: 86-25-83592907 > Email: yccheng.nju at gmail.com > > > -----Inline Attachment Follows----- > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum >
