[Pw_forum] Four Electron Pseudopotnetial for tin: US vs NC-PP

[Lorenzo Paulatto]

On Tue, 08 May 2012 19:45:38 +0200, Giovani Faccin  
<faccin.giovani at gmail.com> wrote:
> 1 - On the 6D line, why a negative number of electrons? Sorry if I'm
> mistaken, but shouldn't that number be positive?

No, this is correct, it only means that the state label is reserved but  
not used in the all-electron calculation. However, I would rather use the  
5D instead of the 6D, but I does not really make any difference for the  
pseudo-wavefunctions.

> 2 - On this same line, why not use the reference energy (0.00), since  
> it's a bound state, as done in 5S and 5P?

Because using a negative occupation number the eigenvalue is not computed  
:-)

>
> 3 - If everything else is ok, the cutoff parameters (the 2.50 and 2.70  
> guys in the 6th and 7th columns) are usually to blame when generation  
> fails.

Indeed, I think it is almost impossible to find a good cutoff radius for  
all the 5 reference wavefunctions, maybe one could start with a  
single-channel pseudopotential; then only add a second channel if  
necessary. However, 2 channels are required for ultrasoft, maybe Sven  
really want to make an USPP in the end.

bests

-- 
Lorenzo Paulatto IdR CNRS @ IMPMC/UPMC - Paris 6
phone: +33 (0)1 44275 084 / skype: paulatz
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