[Pw_forum] Temperature of Raman spectra (Stefano Baroni)

[Stefano Baroni]

Phonon calculations always assume T=0 in QE (as it should be clear  
from the theory that is implemented in the codes, which I assume  
should be known to those who use the code). Unless, you are aiming at  
calculating the raman spectrum of a liquid, but in this case, I would  
beg you to be more specific in your question. Stefano B

On Sep 2, 2009, at 9:20 AM, 刘永铎 wrote:

> Thanks, but my question is still not answered.
> I am asking, how to control the temperature when one use Quantum  
> Espresso (by a tag or something?), what is the default setting of QE  
> on Raman spectra calculation?
>
> best
>
> Yongduo Liu
>
> UCLA
> MSE
>
>
> >
> > Message: 3
> > Date: Wed, 2 Sep 2009 08:39:04 +0200
> > From: Stefano Baroni <baroni at sissa.it>
> > Subject: Re: [Pw_forum] Temperature of Raman spectra
> > To: PWSCF Forum <pw_forum at pwscf.org>
> > Message-ID: <1B8D3293-93F6-45B3-B79B-0263E32468EE at sissa.it>
> > Content-Type: text/plain; charset="gb2312"
> >
> > raman spectra depend on temperature through: 1) Bose occupation
> > factors; 2) the dependence of frequencies on T; 3) the dependence of
> > polarizabilities and their derivatives on T. I presume that (3) is
> > very small, and I am not aware of any attempt to account of suche an
> > effect; 2) is a standard anha rmonic effect that can be  
> approximately
> > accounted for in a number of ways, such as e.g. the quasi-harmonic
> > approximation; 1) is a trivial application of textbook formulas.  
> HTE -
> > Stefano B.
> >
> > On Sep 2, 2009, at 7:48 AM, ??? wrote:
> >
> > > Dear QE users:
> > >
> > > Anybody knows how to control the temperature of Raman
> > > spectra calculation? Is it 0 k by default?
> > >
> > > best
> > >
> > >
> > > Yongduo Liu
> > >
> > > University of California, Los Angeles
> > >
> > > MSE
> > >
> > > ??+??+?? ??????,??MSN????! ?????
> > > _______________________________________________
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> >
> > ---
> > Stefano Baroni - SISSA & DEMOCRITOS National Simulation Center -
> > Trieste
> > http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) /
> > stefanobaroni (skype)
> >
> > La morale est une logique de l'action comme la logique est une  
> morale
> > de la pens?e - Jean Piaget
> >
> > Please, if possible, don't send me MS Word or PowerPoint attachments
> > Why? See: http://www.gnu.org/philosophy/no-word-attachments.html
> >
> >
> >
> >
> >
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---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center -  
Trieste
http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) /  
stefanobaroni (skype)

La morale est une logique de l'action comme la logique est une morale  
de la pensée - Jean Piaget

Please, if possible, don't  send me MS Word or PowerPoint attachments
Why? See:  http://www.gnu.org/philosophy/no-word-attachments.html







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