[Pw_forum] about output wavefunction, charge density and potential

[Stefano Baroni]

On Apr 4, 2006, at 3:02 AM, J G Che wrote:

> 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.

well, this statement is, strictly speaking, not much meaningful until  
one specifies

1) how greedy one is and
2) how large is one's wallet ...

SB

>
> Che
>
>
> ----- 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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---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center -  
Trieste
[+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)

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