[Pw_forum] Reply (was Frequency and zero point energy calculations)

[Gabriele Sclauzero]

Dear Lihui,

oulihui666 wrote:
> Dear Gabriele Sclauzero,
>   I am intend to calculate the frequency of CO2 molecule, so I should 
> perform scf calculation at first, when setting k points as gamma, it 
> will appear a error in the process of calculating frequency, as follows:
> ***********************************************************************
> from phq_readin. error #1
> cannot start from pw.x data file using Gamma-point tricks
> ***********************************************************************

 From what I can understand, this does not mean that you cannot do the calculation for the 
Gamma point only, but rather that the calculation cannot be done using Gamma 
point-specific algorithms (which are much faster than the general ones).
You should anyway be allowed to do the calculation using
K_POINTS AUTOMATIC
1 1 1  0 0 0
which builds a k-point grid containing the Gamma point only, but does not use Gamma-point 
tricks.

You can do the relaxations (and all other expensive pw calculations) using
K_POINTS GAMMA
and then, starting from the optimized atomic positions, do a nscf run using
K_POINTS AUTOMATIC
1 1 1  0 0 0
before the phonon run.

Cheers

GS

P.S: please avoid private mails and stick to the thread you started in the forum, so that 
anyone can help and know when your problem has been solved. Thanks!



> So I do not set k point as gamma in scf calculation.
>  
>  Best regards
>  Lihui 
> 
> --
> ======================================
> Lihui Ou
> PH.D Candidate in Electrochemistry                     
> College of Chemistry and Molecular Science           
> Wuhan University,/430072/,Hubei Province,China 
> /E-mail:oulihui666 at 126.com <mailto:oulihui666 at 126.com>/
> ======================================
> 
> 
> ------------------------------------------------------------------------
> 没有广告的终身免费邮箱,www.yeah.net <http://www.yeah.net/?from=footer>

-- 


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