[Pw_forum] scf

[Stefano Baroni]

Alvaro:

> Hello I am doing a scf calculation system and uses degauss = 0.003

i.e. 40 mev

> and needed change it paar 0001.

i.e. 1.3 mev, very small indeed

> With this new value, the calculation does not converge. What may be  
> happening?

I can only imagine you are using Gaussian smearing for an isolated  
molecule with a degenerate HOMO. the degeneracy is split by the low  
summetry imposed by the supercell, and the electronic structure  
oscillates between the two (or more) states corresponding to each  
partner of the multiplet. when you use a decent gaussian smearing, the  
code makes an average among the degenerate states and it converges.  
when the smearing is instead indecently small, it does not ... As you  
see, from the poor information you are providing, I can only guess.  
Why don't you provide a few bits of imformation, rather than trusting  
our clairvoyance?

>  Regards, Alvaro

I understand that you think we can read your thoughts, but we  
cannot ... and, as you know, we would also like to know the identity  
of those we correspon to in this forum. In the future, please provide  
your complete identity, including your affiliation.

Thanks - Stefano

---
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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