[Pw_forum] Using a pseudopotential with ghosts

[Pietro Bonfa']

Dear prof. Giannozzi,

thank you very much for your comments. The pseudo is indeed used in 3+
state and I didn't encounter any problems during the calculation.

I would like to add that the pseudopotential in the PSlibrary works
perfectly and I was mainly motivated to produce a new pseudopotential by
my wish to deepen my knowledge of pseudopotentials.

Kind regards,
Pietro Bonfa'


On 11/09/12 12:01, Paolo Giannozzi wrote:
> 
> On Nov 7, 2012, at 18:36 , Pietro Bonfa' wrote:
> 
>> The US pseudopotetial works perfectly for all the configurations I
>> tested except for the one with an additional electron i.e. 4s2 4p6  
>> 4d2.0
>> 5s2.0 (the pseudo has semicore s and p in valence) where ghosts  
>> appear.
> 
> negative ions are typically unbound with local or semilocal functionals
> so some funny behavior will be present anyway
> 
>> The logarithmic derivative looks good enough in the energy range ± 8
>> Ry but a (ghost?) spike appear for ~9 Ry in the p channel where the  
>> all
>> electron log derivative is almost flat. [...]
>>
>> So the point is: as long as the pseudopotential is not used in 4d2.0
>> 5s2.0 configuration, is it safe to use it?
> 
> I would say so. At sufficiently high energies the logaritmic  
> derivative of all
> PPs differs anyway from the all-electron one. 9Ry is a rather large  
> energy
> and I don't expect anything physically relevant to happen in that  
> range of
> energies. Moreover Y is more likely to be in a 3+ state than in a -1  
> state.
> No warranty (as usual).
> 
> P.
> ---
> Paolo Giannozzi, Dept of Chemistry&Physics&Environment,
> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
> 
> 
> 
> 
> 
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