[Pw_forum] phonon calculation not converge

[jqli14]

Xiaolin,
     sorry, I have not tried Raman calculation yet.

Jiqiang

在 2015-10-30 00:26:09，"Xiaolin Xu" <xiaolin0314 at gmail.com> 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 <xxu2 at caltech.edu> 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 <jqli14 at fudan.edu.cn> 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" <xiaolin0314 at gmail.com> 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
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