[Pw_forum] "Raman activities" do not converge

[Paolo Giannozzi]

I would carefully check the output instead.
Two values for the Raman activity are clearly 
outliers in a set of well-behaving data points.
They are highly suspect.

P.

On Wed, 2013-05-29 at 09:43 -0700, Sanjeev Gupta wrote:
> Dear Wang
> 
> 
> In my guess, the converging mostly depends on choosing
> pseudopotential, so may be it is the problem, that you are not getting
> converge Raman activity.
> Otherhand, can you check your structure as well as, but i am not sure.
> 
> 
> Best
> Sanjeev
> 
> 
> On Wed, May 29, 2013 at 5:22 AM, xirainbow <nkxirainbow at gmail.com>
> wrote:
>         Dear all:
>                     I calculated the "Raman activity" of
>         diamond(Carbon) using QE-5.0. 
>                     The "Raman activity" changes too much with
>         ecutwfc.
>                     Could you give me some help?
>         
>         
>         Calculational results of "Raman activity variation with
>         ecutwfc" ("14*14*14 kmesh).
>            ecutwfc(Ry)      Freq(cm-1)          Raman
>         activity(A^4/amu)
>            65                     1330.23                  68.9754
>            100                   1330.65                  68.9674
>            110                   1330.50              3066.0811
>            120                   1330.48                  15.1570
>            130                   1330.47                  68.9545
>         
>         
>         The following is input of pw.x and ph.x:
>         INPUT of SCF:
>          &control
>             calculation='scf',
>             disk_io='low',
>             restart_mode='from_scratch',
>             prefix='diamond.$i'
>             pseudo_dir = '/home/lykong/hwang/espresso-5.0/pseudo',
>             outdir='/home/lykong/hwang/tmp'
>          /
>          &system
>             ibrav = 0, celldm(1) = 1.88972687777436, nat= 2, ntyp= 1,
>             ecutwfc = $i
>          /
>          &electrons
>             mixing_beta = 0.7
>             conv_thr =  1.0d-8
>          /
>         ATOMIC_SPECIES
>          C   12.01   C.pw-mt_fhi.UPF
>         ATOMIC_POSITIONS {crystal}
>         C   0.000000000         0.000000000         0.00000000
>         C   0.250000000         0.250000000         0.25000000
>         CELL_PARAMETERS
>            1.758613117   1.758613117   0.000000000
>            1.758613117   0.000000000   1.758613117
>            0.000000000   1.758613117   1.758613117
>         
>         
>         
>         
>         INPUT of PHONON:
>         phonons of diamond at Gamma
>          &inputph
>           tr2_ph=1.0d-14,
>           alpha_mix=0.7
>           prefix='diamond.$i'
>           epsil=.true.,
>           lraman=.true.,
>           amass(1)=12.01,
>           outdir='/home/lykong/hwang/tmp'
>           fildyn='diamond.$i.dynG',
>           reduce_io=.TRUE.
>          /
>         0.0 0.0 0.0
>         
>         
>                    
>         
>         
>         -- 
>         ____________________________________
>         Hui Wang
>         School of physics, Fudan University, Shanghai, China
>         
>         _______________________________________________
>         Pw_forum mailing list
>         Pw_forum at pwscf.org
>         http://pwscf.org/mailman/listinfo/pw_forum
> 
> 
> 
> 
> -- 
> With Best Regards,
> 
> 
> ------------------------------------
> Dr. Sanjeev Kumar Gupta
> Fulbright Post-Doctoral Scholar
> Dept. of Physics
> Michigan Technological University 
> 1400 Townsend Drive, Houghton 
> MI 49931, USA 
> ------------------------------------
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-- 
Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222