[Pw_forum] K-points implemented in TDDFPT?

[Giuseppe Mattioli]

Dear Stefano (and all)
I would stick a related question to the thread... I've tried to perform a TDDFPT (QE 5.0) 
calculation of an O2 molecule (gamma, nspin=2, tot_magnetization=2.0). Previous versions of the 
turbo_lanczos code would have stopped and complained. The current version only says

     Lanczos linear response spectrum calculation
     Number of Lanczos iterations =   1000
     Message from routine lr_init_nfo:
     occupation numbers probably wrong

does it say that he cannot deal with 7 spin up and 5 spin down electrons, and it is calculating the 
response of some dummy charge density, or is there something "more exotic" behind?

Thanks in advance

Giuseppe


On Tuesday 05 June 2012 23:56:45 Stefano Baroni wrote:
> On Jun 5, 2012, at 4:50 PM, Huang, Jingsong wrote:
> > Dear all,
> > 
> > Didn’t see a forum for TDDFPT so I can only ask my question here at PWSCF
> > forum.
> > 
> > A couple of threads in April 2011 mentioned that TDDFPT worked only for
> > Gamma point. That’s the case with earlier version of Quantum Espresso.
> > Just wondering if the k-points algorithm has been implemented in the
> > TDDFPT that is interfaced with the latest Quantum Espresso 5.0?
> 
> NO
> 
> > The lr_readin.f90 shows a comment that “K-points implemented but still
> > unsupported (use at your own risk!)”. However, if k-point is used, the
> > calculation stops right away with an iosys error message: k-point
> > algorithm is not tested yet.
> 
> see above
> 
> > I would like to calculate UV-vis for an extended system. Any suggestions?
> > Thanks a lot.
> 
> 1) go into the code and implement k-point sampling
> 2) wait for a future release
> 3) use a different code (I think YAMBO should have some tddft capabilities,
> in addition to many more sophisticated options based on MBPT)
> 
> In all cases, beware of the well known limitations of current TDDFT for
> extnded systems, when using (semi-) local functionals
> 
> S.
> 
> ---
> 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

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   Giuseppe Mattioli                            
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