[Pw_forum] phonon calculation not converge

[Xiaolin Xu]

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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>
>
>
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