[Pw_forum] about output wavefunction, charge density and potential

J G Che jgche at fudan.edu.cn
Tue Apr 4 03:02:19 CEST 2006

Dear Paolo:

Thanks for you replying. 

Do you mean that pwscf uses disk to store wavefunctions? 

I think it is not necessary to store wavefunction on disk, since now the RAM is very sheap. 


----- Original Message ----- 
From: "Paolo Giannozzi" <giannozz at nest.sns.it>
To: <pw_forum at pwscf.org>
Sent: Tuesday, April 04, 2006 2:55 AM
Subject: Re: [Pw_forum] about output wavefunction, charge density and potential

> On Saturday 01 April 2006 05:10, J G Che wrote:
> > I find that in each iterative, wavefunction, potential and charge density
> > will be saved on disk. Who knows how to output these once only when 
> > the self-consistent is reached. Thanks!
> - if you have more than one k-point per processor, you have to save
>   wavefunctions to disk. It would be possible to store them into memory 
>   but it would require extensive changes to the code (and a lot of memory)
> - if you have just one k-point and do not specify disk_io='high' the
>   code will write wavefunctions only at convergence
> - the charge density and potential are written at each scf step.
>   This is a behavior that could be changed with simple modifications
>   in the code. These arrays however are usually much smaller than
>   the wavefunctions.
> - unless you specify disk_io='high', auxiliary arrays used for
>   self-consistency are not written to disk but stored
> - other files are typically small
> Paolo
> -- 
> Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
> Scuola Normale Superiore    Phone:   +39/050-509876, Fax:-563513 
> Piazza dei Cavalieri 7      I-56126 Pisa, Italy
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