[Pw_forum] Using a PBE pp but set Xc type to LDA

[Lorenzo Paulatto]

Dear 耿慧远,

the pseudopotential file contains the (pseudized) potential that the 
atom's nucleus and core electrons apply on the surrounding chemical 
environment. This potential depends on the functional used o do the 
all-electron reference calculation for the atom. If you do this 
calculation with PZ you will get a PZ local potential, if you do it with 
PBE you will get a PBE local potential.

Doing the local potential with a functional and then using in a 
plane-waves calculation with another functional is inconsistent. You may 
get results that fit better some experimental data, but this is purely 
accidental and does not give any insight about the reason of the 
improvement.

kind regards


On 19/06/17 12:28, 耿慧远 wrote:
> Dear colleagues,
>
> I read a slides wrote by Dr. Paolo Giannozzi on the lattice constant 
> of graphite. /
> /If we set input_dft='PZ' but with a PBE pseudopotential, the obtained 
> lattice constant is very close to experiment.
> If we set input_dft='PZ' and with a LDA pseudopotential, the obtained 
> lattice constant is far smaller than experiment.
>
> I understand that LDA can be a rough replacement fore the vdW 
> correction. But why the PP must be generated in the PBE form ?
>
> Best regards,
>
> Huiyuan Geng
> Harbin Institute of Technology, China
>
> /
> /
>
>
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-- 
Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
phone: +33 (0)1 442 79822 / skype: paulatz
www:   http://www-int.impmc.upmc.fr/~paulatto/
mail:  23-24/423 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05

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