[Pw_forum] consistent Fe,Se,Te pseudopotential files

[Stefano de Gironcoli]

The reason why USPP have been introduced is not for some form of 
masochism but because for certain elements of the first row (C-N-O-F) or 
for first row transition metals or rare earths NCPP would require very 
high cutoff. Most other elements (including Se,Te) can be treated with 
much lower cutoffs and do not need USPP construction...
It is convenient therefore to use USPP for the hard elements while you 
can stick to NCPP when this is not needed.
And you CAN mix different types.

And always test convergence of your calculations.

stefano

Gianluca Giovannetti wrote:
> Dear Paolo,
>
> thank you for the reply.
> Probably i`m missing something in your statement. :-)
> Are you suggesting to use
>
> Fe.pbe-sp-van.UPF<http://www.quantum-espresso.org/pseudo/1.3/UPF/Fe.pbe-sp-van.UPF>
>  <http://www.quantum-espresso.org/pseudo/1.3/UPF/Te.pbe-rrkj.UPF>
> Te.pbe-rrkj.UPF<http://www.quantum-espresso.org/pseudo/1.3/UPF/Te.pbe-rrkj.UPF>
> Se.pbe-van.UPF<http://www.quantum-espresso.org/pseudo/1.3/UPF/Se.pbe-van.UPF>
>
> pseudopotential files evenif there are belonging to different types?
>
> cheers,
>
> Gianluca
>
> On Mon, Jun 21, 2010 at 9:59 AM, Paolo Giannozzi <giannozz at democritos.it>wrote:
>
>   
>> On Monday 21 June 2010 08:04, Gianluca Giovannetti wrote:
>>
>>     
>>> i would appreciate much more to have Te Vanderbilt ultrasoft
>>> pseudopotential.
>>>       
>> why? the big advantage of ultrasoft PPs is to require a much
>> smaller cutoff. In the case of Fe-Te-Se systems, Fe is by far
>> the hardest element. The cutoff needed for ultrasoft Fe might
>> well be sufficient for norm-conserving Te (and Se as well).
>>
>> P.
>> --
>> Paolo Giannozzi, Democritos and Udine University
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>>     
>
>   
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