[Pw_forum] different PP gives different result, why???

[Lorenzo Paulatto]

On 02/05/2014 11:18 AM, Lorenzo Paulatto wrote:
> On 02/05/2014 10:56 AM, Ganjar Kurniawan wrote:
>> I am trying to compare the calculation of the Lithium bulk system 
>> which has BCC structure with lattice constant is 6.597 bohr using 
>> different pseudopotential between Li.pbe-s-rrkjus_psl.0.2.1.UPF and 
>> Li.pw91-n-van.UPF.
>>
>> the result give different of total energy are -14.82521305 Ry and 
>> -1.82426227 Ry respectively...
>>
>>
>
I also noticed that the latter pseudotential does not include semi-core, 
while the latter does. Even in the ideal case of perfect PAW dataset, 
the value returned by pw.x is only the valence energy, it cannot keep in 
account frozen core electrons. Using two similar pseudopotential the 
results would be more similar, but it is still a mistake to compare them

regards



> -- 
> Dr. Lorenzo Paulatto
> IdR @ IMPMC -- CNRS & Université Paris 6
> +33 (0)1 44 275 084 / skype: paulatz
> http://www-int.impmc.upmc.fr/~paulatto/
> 23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05
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