[Pw_forum] Spectra from GW and TDDFPT

[jiayudai]

Dear Giuseppe,

I think the current TDDFPT can only work without spin polarization, is it? Besides, i do not know is there any limitation in theory to deal with more k_points and metallic case? In my test, it can not deal with the molecule such as NO2, since it needs the smearing method in the scf calculations.

Thanks.

Jiayu


From: Giuseppe Mattioli <giuseppe.mattioli at mlib.ism.cnr.it>
Subject: Re: [Pw_forum] Spectra from GW and TDDFPT
To: PWSCF Forum <pw_forum at pwscf.org>
Message-ID: <201104131649.52909.giuseppe.mattioli at mlib.ism.cnr.it>
Content-Type: text/plain; charset="utf-8"

Dear Jiayu
Yes, it is. With only one additional warning: the TDDFPT code works only at
Gamma (and fixed occupations). It is not designed to deal with periodic
systems where you need k-points, but (in my experience) it works well with
molecules.

On Wednesday 13 April 2011 15:20:59 jiayudai wrote:
> Thanks for your recommendation and reply, mohsen and Giuseppe. So,
> Giuseppe, i understand what 's your meaning is that the GWW and TDDFPT in
> QE distribution (4.3) can be used for different purposes, but they are
> both accurate in their fields. In addition, they both have the advantage of
> efficient computation speed becuase they used different method from the
> tranditional methods. Is it?
>
> Thanks again.
>
> Jiayu
>
> > Pw_forum at pwscf.org
>
> From: Giuseppe Mattioli <giuseppe.mattioli at mlib.ism.cnr.it>
> Subject: Re: [Pw_forum] Spectra from GW and TDDFPT
> To: pw_forum at pwscf.org
> Message-ID: <201104131432.02080.giuseppe.mattioli at mlib.ism.cnr.it>
> Content-Type: text/plain; charset="utf-8"
>
>
> And, practically speaking, you can obtain corrected (i.e., quasiparticle)
> eigenvalues by using GWW, and absorption spectra by using turbo_lanczos,
> that is, the GW and TDDFPT current implementations that you find embedded
> into the QE (4.3) distribution. Within the above limitations, the
> computational cost of both methods can be considered rather low.
> HTH
>
> Giuseppe
>
> On Wednesday 13 April 2011 13:59:50 mohsen modaresi wrote:
> > Dear Jiayu Dai,
> > Prof. R. Godby is one of the most famous scientist who worked on
> > many-body theory. i think this lecture should be help full for you.
> > {Many-Body Theory and DFT / TDDFT
> > Rex Godby"
> > http://docs.google.com/viewer?a=v&q=cache:gBMHk9QaO3cJ:www.tddft.org/TDDF
> >T2
> > 006/2006tddft/docs/school/Godby.pdf+TDDFT+and+GW&hl=en&pid=bl&srcid=ADGEE
> >Siq
> > 9Au0dGZsFvyPUtLL9nEaPg44xzN8NzkJiiguvyAdyTFUpucP8XOKWMyrKammwPLMDfQZncmtg
> >oh8
> > NA-PFsRKaUxsRnrdbFId7a7dW2mkkOHqrr4TFgpalZC775KF1njtbF4p&sig=AHIEtbTLv5Xg
> >Sx5 m0wfXO3sMV7vzJlgOtg&pli=1
> >
> > Hope it helps,
> >
> >
> > 2011/4/13 jiayudai <daijiayu at nudt.edu.cn>
> >
> > > Dear users,
> > >
> > > It is well known that GW method can give much more accurate band gap
> > > since it considers many body interaction, and thus it can give more
> > > accurate optical properties. What i am thinking is that what's the
> > > difference between the optical properties from TDDFPT and GW. I mean,
> > > TDDFPT has the same accuracy as the GW method? or what's the advantage
> > > of TDDFPT over the GW except the computationl cost?
> > >
> > > Thanks a lot.
> > >
> > > Jiayu
> > >
> > >
> > > -------------------------------------------
> > > Jiayu Dai
> > > Department of PhysicsNational University of Defense Technology,
> > > Changsha, 410073, P R China
> > > -----------------------------------------
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