Dear Ari and Jiqiang, Thank you so much for all the instructions! Yes I ran pw.x using K_POINTS automatic // 1 1 1 0 0 0 before running ph.x. I will increase the cut-off energy and hope it will work!
Lin On Thu, Oct 29, 2015 at 3:34 PM, Ari P Seitsonen <[email protected]> wrote: > > Dear Xiaolin, Jiqiang et co, > > Did you re-run 'pw.x' using the 'K_POINTS automatic // 1 1 1 0 0 0' > before trying to run 'ph.x'? > > On the other hand the number of k points depends on your system, the > amount of band dispersion it etc. So indeed, if the electronic structure is > not yet converged well with only Gamma point, it is better to apply more k > points. This you can do by testing for the convergence. > > By the way, the cut-off energy of 80 Ry is probably far too low for the > HGH/GTH pseudo potentials that you have used: We used 125 Ry for the oxygen > - I would guess that the one for iron, maybe also lithium - and that was in > molecular dynamics; for phonons I would expect even higher a value > necessary. > > Greetings, > > apsi > > > -=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=- > Ari Paavo Seitsonen / [email protected] / http://www.iki.fi/~apsi/ > Ecole Normale Supérieure (ENS), Département de Chimie, Paris > Mobile (F) : +33 789 37 24 25 (CH) : +41 79 71 90 935 > > > > >> 在 2015-10-30 00:26:09，"Xiaolin Xu" <[email protected]> 写道： >> >> Hi Jiqiang, >>> >>> >>> Thank you very much for your help! >>> I tried using only gamma point, but I got an error message when I >>> calculated phonon saying "can't start from gamma tricks...". Besides, I >>> need to calculate the raman frequencies after phonon calculation, so I >>> think it's better if I use more k points. >>> >>> Have you tried Raman calculation? Could you give me more advice? >>> >>> Best, >>> >>> Xiaolin >>> >>> >>> On Wed, Oct 28, 2015 at 10:21 PM, Xiaolin Xu <[email protected]> wrote: >>> >>> Hi Jiqiang, >>> >>> Thank you very much for your help! >>> I tried using only gamma point, but I got an error message when I >>> calculated phonon saying "can't start from gamma tricks...". Besides, I >>> need to calculate the raman frequencies after phonon calculation, so I >>> think it's better if I use more k points. >>> >>> Have you tried Raman calculation? Could you give me more advice? >>> >>> Best, >>> >>> Xiaolin >>> >>> >>> On Wed, Oct 28, 2015 at 6:20 PM, jqli14 <[email protected]> wrote: >>> (1)employ k_points gamma instead of k_pionts automatic 1 1 1 0 0 0, >>> although both give the same result, but the later does not call the gamma >>> point specific algorithm to speed the calculation. >>> (2)if it can not converge within handreds of electronic steps, reduce >>> the value of mixing_beta or change the mixing_mode. >>> >>> Jiqiang Li >>> >>> >>> 在 2015-10-29 07:57:58，"Xiaolin Xu" <[email protected]> 写道： >>> >>> Dear all, >>>> >>>> I was doing phonon dispersion calculations for lithium iron phosphate. >>>> However, the calculation speed is really slow and it does not converge. Is >>>> this because my system is too big? There are 28 atoms in the unit cell. My >>>> input file is like this: >>>> (1) >>>> >>>> >>>> &CONTROL >>>> calculation = "scf", >>>> pseudo_dir = "/home/xiaolin/pseudo", >>>> outdir = "/home/xiaolin/test2", >>>> tstress=.true., >>>> tprnfor=.true., >>>> nstep=100, >>>> / >>>> >>>> &SYSTEM >>>> ibrav = 8, >>>> celldm(1) = 19.749526 >>>> celldm(2) = 0.582432, >>>> celldm(3) = 0.454693, >>>> nat = 28, >>>> ntyp = 4, >>>> ecutwfc = 80.D0, >>>> / >>>> >>>> &ELECTRONS >>>> mixing_beta = 0.7, >>>> / >>>> >>>> &IONS >>>> / >>>> >>>> ATOMIC_SPECIES >>>> >>>> Li 6.941 Li.pbe-s-hgh.UPF >>>> Fe 55.845 Fe.pbe-sp-hgh.UPF >>>> P 30.97376 P.pbe-hgh.UPF >>>> O 15.9994 O.pbe-hgh.UPF >>>> ATOMIC_POSITIONS (alat) >>>> Li 0 0 0 >>>> ... >>>> K_POINTS (automatic) >>>> 1 1 1 0 0 0 >>>> >>>> (2) >>>> >>>> Normal modes for lifepo4 >>>> &inputph >>>> tr2_ph=1.5d-5, >>>> amass(1)=6.941, >>>> amass(2)=55.845, >>>> amass(3)=30.97376, >>>> amass(4)=15.9994, >>>> outdir = '/home/xiaolin/test2', >>>> trans=.true., >>>> asr=.true., >>>> nogg=.true., >>>> fildyn='dmat.lifepo4' >>>> / >>>> 0.0 0.0 0.0 >>>> >>>> >>>> >>>> Thank you in advance! >>>> >>>> >>>> Lin >>>> >>> >>> >>> >>> > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum >
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