[CP2K-user] optimize RI basis

[Katarina S.]

Dear all,
I am studying a binding of water in aluminosilicate systems using RPA. 
However, available basis set (cc-QZ for H and O and cc-TZ) gives too big 
BSSE - it is between 15-20 kJ/mol. BSSE on PBE level is small (< 5 kJ/mol) 
so I assume it is due to auxiliary basis. Therefore, I would like to 
re-optimize RI basis sets for Al and Si atoms. I had look on regtests: 
cp2k-3.0/tests/QS/regtest-ri-mp2/opt_basis_O_auto_gen.inp.  and  
opt_basis_O_num_func.inp and they run smoothly. I looked also on the 
tutorial given in 
https://www.cp2k.org/_media/events:2015_cecam_tutorial:wilhelm_posthf.pdf
However, I am still not sure how to continue with my system. I have several 
questions:
1) Because I will run RPA, shall I turn on  the PBE functional in XC 
section for basis set optimization?
2) If I optimize basis set for a simple system such as Al atom to which 
extend are the parameters reliable/transferable? 
3) Alternatively I looked on BASIS_def2_QZVP_RI_ALL. Is it possible to 
combine all electron basis with pseudopotentials?  I run the calculations 
in combination with GTH potentials and I see that the results are very 
different than when I use cc-QZ basis (adsorption energy of water differs 
about 20-30 kJ/mol), so I do not trust them much.

Thank you for your help!
Kind regards,
Katarina
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