ABINIT Discussion Forums

Hi

I was doing some simple test with ABINIT8.10.3 and using the ONCVPSP-PW-PDv0.4 pseudo potentials

https://github.com/abinit/pseudo_dojo/t ... jo/pseudos

And in my calculation, the code says that

--- !WARNING
src_file: m_pspini.F90
src_line: 1088
message: |
Pseudopotential file pspxc= -1012,
not equal to input ixc= 7.
These parameters must agree to get the same xc
in ABINIT code as in psp construction.
Action: check psp design or input file.
Assume experienced user. Execution will continue.


This message i got is normal and i know it was causing by different XC functional in the psp and the calculation.
But there are two questions.

1,What's the XC functional type with index -1012 ? I can't find any index or information for it on the variable page.
2,In order to find the XC functional. I find the .out format with the psp file, and it says
functional part 1 Slater exchange
functional part 2 Perdew & Wang
in this situation, how can i determined what ixc should i use for the calculation?

Can anyone help?

Cheers
Andy

Dear Andy,
The negative ixc is linked to libxc library:
https://www.tddft.org/programs/libxc/functionals/

The positive values are internal exchange-correlation implemented in Abinit.
In your case ixc=-1012 and ixc=7 are actually the same such that it is fine. What would be more problematic is to use two very different ixc in the pseudo and in the inout (GGA vs LDA for example), thought it often works fine... This message is just to warn the user that there is a difference and the user is aware of it.

If you don't specify ixc in your input it'll use the one from the pseudo by default and you'll be sure to be consistent.

Best wishes,
Eric

Dear Eric

Thanks for the info.The calculation successes and work perfectly,.

Cheers,
Andy Hsu