[Pw_forum] ld1.x problem (not really)

[Stefano Baroni]

On Jan 25, 2008, at 5:02 PM, Lorenzo Paulatto wrote:

>
> On Fri, January 25, 2008 14:30, Lazaro Calderin wrote:
>> Those ghosts are out of the interval of -2.5 to 0 Ry which one would
>> expect to be the important one for the bonding in this case.
>
> This is an optimistic assumption; in my modest experience I have found
> that a ghosts at E < E_atomic_state always breaks the potential, at  
> E < 1
> Ry usually breaks it, and at E < 5~6 Ry causes erratic and slow
> convergence.
>
> Try to test it in pw in a single atom configuration: it may  
> converge fine
> as long as you start from atomic wavefunctions. But if you start  
> with some
> random wavefunctions it converge slowly to a deeper "haunted"
> configuration.

that's the fault of the Ritz's variational principle, boys!

SB

---
Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center -  
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