[Pw_forum] occupations fixed

[Lorenzo Paulatto]

In data 07 ottobre 2009 alle ore 09:24:28, udayagiri sai babu  
<udayagiri3 at gmail.com> ha scritto:

> In the archive I have seen a discussion suggesting use of  
> occupations=fixed to find out the ground state energy of isolated oxygen  
> atom accurately. Can I use the same (occupations=fixed) for metal also.  
> Because in the pw
> document it is told to use only for insulators.


Dear U,
for isolated atoms you can always use fixed occupations: as you use only  
use the Gamma point, bands are actually flat. Nevertheless it may be  
difficult to reach the ground state in some cases, I suggest using a small  
smearing which should give exactly the same result but makes convergence  
faster.

I see you have already asked how to compute the ground state for a Ti atom  
(e.g.  
<http://www.democritos.it/pipermail/pw_forum/2009-September/014246.html>),  
which actually is a metal... why don't you tell us your problem, instead  
of your guess for a solution?

best regards

-- 
Lorenzo Paulatto
SISSA  &  DEMOCRITOS (Trieste)
phone: +39 040 3787 511
skype: paulatz
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