[Pw_forum] choosing degauss value

[Stefano Baroni]

Dear Salbadu: I am sure this has been explained many, many time on  
this forum,  and I would like to invite you to search old posts. In a  
nutshell, mathematically allows to turn the integration of a  
discontinuous function (the T=0 Fermi distribution) into that of a  
continuous function; physically, degauss can be seen as a kind of  
fictitious temperature (the Fermi distribution is continuous at T=/=  
0), and some of the tricks that are used in conjuction with Gaussian  
spearing (e.g. for the calculation of Hellmann-Feynman forces)  
actually take advantage from this physical analogy. If you want to  
know/understand more _after_  your browse the past posts in this form  
and read some of the relevant literature, please revert to us. Stefano  
Baroni

On Sep 7, 2009, at 8:35 AM, udayagiri sai babu wrote:

> Dear all
> can somebody tell me how to choose a correct degauss value for an  
> SCF calculation and also the physics behind it.
>
> -- 
> U.Saibabu
> PhD student,
> Deformation mechanisms modeling group,
> Materials engineering department,
> IISc Bangalore,
> India.
>
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> Pw_forum at pwscf.org
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---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center -  
Trieste
http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) /  
stefanobaroni (skype)

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de la pensée - Jean Piaget

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