[Pw_forum] Question about potential (pp tool)

[Malgorzata Wierzbowska]

On Wed, 4 Oct 2006, degironc wrote:


> In the KB fully non-local form different choices of lloc therefore produce 
> slightly different pseudopotentials that  all gives the same results on the 
> atomic configuration used for the KB projection and should behave similarly 
> provided they do not have GHOST states.  Usually lloc=lmax (or lmax+1) would 
> be the most "physical" choice but this is not always possible due to the 
> ghosts problem above.
>

   And for the transition metals lloc=0. For the choice of lloc, such that
there are no ghost states in KB-form,
see Fuch and Scheffler CPC vol. 119, 67-98 (1999),
(pages 81-83 explain lloc).

   Gosia



> Using UPF format this little algebra has alredy been done in the 
> pseudopotential file and Vloc_at above is given direclty in the PP_LOCAL 
> field while the KB projections = DeltaV*Psi_atomic are given in the PP_BETA 
> fields and lloc is not needed anymore.
>
> Sorry if  this explanation confuses you again...
>
> stefano
>
> Lilia Boeri wrote:
>
>> dear Stefano,
>> 
>> thanks a lot. Reading another message that you wrote me some time ago, I 
>> understand that when a psp is read from PWSCF one of the l components is 
>> assumed as "local" potential, while the other channels are considered 
>> non-local and obtained from the first by projection. Is this correct?
>> 
>> If this is only a numerical trick, the results should not depend on which 
>> channel I choose as "local", is this correct? thanks,
>> Lilia
>> 
>> On Wed, 4 Oct 2006, degironc wrote:
>> 
>> 
>>> It is the total local potential which inside the core region is 
>>> meaningless.
>>> Only the region outside the core is "physical" .
>>> stefano
>>> 
>>> Lilia Boeri wrote:
>>> 
>>> 
>>>> Dear PWSCF users,
>>>> 
>>>> I am sorry for the somehow stupid question, but the more I think about it
>>>> the more I get confused... The question is: what is exactly the "total"
>>>> potential which is given by pp.x when plot_num is set to 1?
>>>> The manual says:
>>>> 1=total potential V_bare+V_H + V_xc
>>>> 
>>>> my question is: what is V_bare? Is it the local potential or some sort of
>>>> total average potential?
>>>> 
>>>> Thanks a lot,
>>>> Lilia
>>>> 
>>>> 
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>
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