[Pw_forum] error got by using program pp.x to deal with the input file

[Stefano Baroni]

In addition to Axel's suggestions, I would also recommend to use a  
minimum critical mind. Much to my blame, I know very little of the  
functionality of pp.x, but from your post I can guess that you are  
trying to calculate some density of states (DOS): ain't you? Have you  
aver esked yourself HOW a continuous DOS is calculated from a number  
of DISCRETE tates? (yes, QE as well as virtually any electronic- 
structure codes approximate continuous spectra with a number of  
discrete states) Have you ever asked yourself what Gaussian smearing  
is meant for? (answer: to broaden a discreet peak into a pseduo- 
continuous spectrum) If not, do it now. From the answer, you will get  
a hint for your problem. Stefano

PS: broadening is not the only way to obtain DOS's. In a periodic  
system the tetrahedron method does it better, but I am not sure that  
this method is used by pp.x in you case. In any event, google  
"tetrahedron" and "density of states" and get an idea of what the  
method is/does.

On Jan 22, 2009, at 4:40 AM, Axel Kohlmeyer wrote:

> On Thu, 22 Jan 2009, Weiguang Chen wrote:
>
> WC> Hi,
> WC> Thanks for your respondence quickly.
> WC> But there is no tag to set gaussian broadening in the input-file  
> of
> WC> pp.x .   Is this mean that I should set this value in scf  
> calculation?
>
> where else?
>
> WC> In fact,  I have used gaussian broadening in scf calculation.
> WC>
> WC> I set the gaussian broadening in scf calculation as follows:
> WC>                      occupations='smearing',
> WC> smearing='gauss',
> WC> degauss=0.01,
>
> please provide a complete script or set of inputs that
> reproduces this behavior, without requiring access to
> a supercomputer. perhaps then somebody can tell you
> what went wrong.
>
> i just slapped together a stupid example and "it works for me(tm)"
>
> have you run some other calculation in between that
> would modify the saved wavefunction?
>
> axel.
>
>
> WC>
> WC> Thanks
> WC> Chen Weiguang
> WC> On Thu, Jan 22, 2009 at 2:55 AM,  <giannozz at democritos.it> wrote:
> WC> > Quoting Weiguang Chen <chenweiguang82 at gmail.com>:
> WC> >
> WC> >> I am a newbie about pwscf and i want to know what parameter  
> should
> WC> >> been modified. Could you tell me more detail why this problem  
> happen?
> WC> >
> WC> > documentation in Doc/INPUT_PP.*
> WC> >
> WC> > Paolo
> WC> >
> WC> >
> WC> > ----------------------------------------------------------------
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> WC> >
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> WC> >
> WC>
> WC>
> WC>
> WC>
>
> -- 
> = 
> ======================================================================
> Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http:// 
> www.cmm.upenn.edu
>   Center for Molecular Modeling   --   University of Pennsylvania
> Department of Chemistry, 231 S.34th Street, Philadelphia, PA  
> 19104-6323
> tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
> = 
> ======================================================================
> If you make something idiot-proof, the universe creates a better  
> idiot.
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---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center -  
Trieste
http://www.sissa.it/~baroni / [+39] 040 3787 406 (tel) -528 (fax) /  
stefanobaroni (skype)

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de la pensée - Jean Piaget

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