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Dear all,
I am a VASP new user.
I have questions about INCAR and POTCAR. The questions are listed as follows.
1.I would like to use GGA to do bulk calculation, the INCAR looks like
ISTART = 0
ICHARG= 2
ENCUT = 400
ISMEAR = -5
SIGMA = 0.2
GGA = PW
IBRION = 2
ISIF = 2
NSW = 600
The job could not be done, and I got an error message that is “ You enforced a specific xc-type in the INCAR file, a different type was found on the POTCAR file.�
I got the POTCAR from VASP library,pot_gga. I do not know where wrong is?

2. Another question is what the differences between pot and pot_gga? (In the VASP library, I can get the POTCAR for calculation from pot or pot_gga.)

Any advise will be appreciated!!

1) this message is just a warning, it cannot be the reason why a job crashes. However, in your case it is sufficient if you just take the GGA POTCAR, you need not specify GGA explicitely
2) please read the vasp-worksop tutorials.