[Pw_forum] ph.x can only address LDA potentials? (Gabriele Sclauzero)

[刘永铎]

Ok i know where was my problem. Thank Gabriele!

I was not using the equilibrium configuration under that potential..


best

Yongduo


UCLA
MSE department 

> From: pw_forum-request at pwscf.org
> Subject: Pw_forum Digest, Vol 26, Issue 76
> To: pw_forum at pwscf.org
> Date: Fri, 28 Aug 2009 18:58:23 +0200
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> Today's Topics:
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>    1. Re: ph.x can only address LDA potentials? (Gabriele Sclauzero)
>    2. << running QE in parallel >> (I. Camps)
>    3. Re: << running QE in parallel >> (Lorenzo Paulatto)
>    4. Re: << running QE in parallel >> (I. Camps)
>    5. Re: << running QE in parallel >> (Lorenzo Paulatto)
>    6. Re: << running QE in parallel >> (I. Camps)
>    7. Re: << running QE in parallel >> (Duy Le)
>    8. Correlated wave-function in real space (Andreas Linscheid)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Fri, 28 Aug 2009 08:56:57 +0200
> From: Gabriele Sclauzero <sclauzer at sissa.it>
> Subject: Re: [Pw_forum] ph.x can only address LDA potentials?
> To: PWSCF Forum <pw_forum at pwscf.org>
> Message-ID: <4A977FB9.7070002 at sissa.it>
> Content-Type: text/plain; charset=UTF-8; format=flowed
> 
> Dear pw user,
> 
> ??? wrote:
> > Dear Pw user:
> > 
> > 
> >      I am trying to calculate Raman spectrum of some stuff. But it seems 
> > that the ph.x complains whenever I use potentials other than LDA. It 
> > gives error messages like:
> >   
> >     * The phonon code with ### and raman, elop or elph is not yet 
> > available.*
> 
> What are you hiding under ###? The only error message that I could find in the ph.x 
> sources and can match yours is:
> 
> [sclauzer at brenta:/scratch/sclauzer-exec/espresso-4.1/PH]$ grep available *.f90
> ...
> phq_readin.f90:     'The phonon code with paw and raman, elop or elph is not yet available',1)
> ...
> 
> This message does not mean that you cannot use any DFT functional other than LDA, but that 
> you cannot use PAW together with Raman or El-Ph coupling calculations for instance. You 
> can always use ultrasoft pseudopotentials (US-PPs) instead of projector augmented waves, 
> and I think that with US PPs there are no such limitations. For PAW, well you may have to 
> wait some time, or think about implementing it yourself and then contributing it to the 
> community.
> 
> 
> >  
> >      So, is the lda-potentail our only choice?   But the calculated 
> > Raman mode is very bad comparative to the experimental results. For 
> > instance, SiH4, it gives:
> > 
> > #  mode   [cm-1]     [THz]      IR           Raman     depol
> >     1      0.00    0.0000    0.0000         0.0791    0.7500
> >     2      0.00    0.0000    0.0000         0.1194    0.7500
> >     3      0.00    0.0000    0.0000         0.0679    0.7500
> >     4      0.00    0.0000    0.0000         0.0970    0.7500
> >     5      0.00    0.0000    0.0000         0.0051    0.7500
> >     6      0.00    0.0000    0.0000         0.0235    0.7500
> >     7    634.67   19.0268    1.0902         1.1145    0.7500
> >     8    634.67   19.0268    1.0902         1.1145    0.7500
> >     9    634.67   19.0268    1.0902         1.1145    0.7500
> >    10    819.69   24.5735    0.0000         8.4725    0.7500
> >    11    819.69   24.5735    0.0000         8.4725    0.7500
> > *   12   2524.31   75.6765    0.0000       267.0683    0.0000*    ? this 
> > one?
> >    13   2546.65   76.3462    3.3789        81.6301    0.7500
> >    14   2546.65   76.3462    3.3789        81.6301    0.7500
> >    15   2546.65   76.3462    3.3789        81.6301    0.7500
> > 
> > 
> > but the experimental value is 2187 cm-1
> 
> It may be that LDA overestimates a frequency. Anyway, are you sure you converged with 
> respect to all relevant parameters, cut-offs,...? What is the lattice parameter you used? 
> ...?
> 
> regards,
> 
> Gabriele
> 
> 
> > 
> > 
> > best
> > 
> > 
> > Yongduo
> > 
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> -- 
> 
> 
> o ------------------------------------------------ o
> | Gabriele Sclauzero, PhD Student                  |
> | c/o:   SISSA & CNR-INFM Democritos,              |
> |        via Beirut 2-4, 34014 Trieste (Italy)     |
> | email: sclauzer at sissa.it                         |
> | phone: +39 040 3787 511                          |
> | skype: gurlonotturno                             |
> o ------------------------------------------------ o
> 
> 


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