[molpro-user] default fitting basis for F12

[Boris Averkiev]

I have question about density fitting basis sets for F12 methods I calculated Cl atom.

When I specified basis one way
geomtyp=zmat
geometry={ Cl }
basis=aug-cc-pvqz
rhf
rmp2-F12

MOLPRO used the following basis sets:

                          Density fitting integral evaluation by F. R. Manby, 2003,2007
                                      
Basis set CC-PVQZ/JKFIT generated.      Number of basis functions:   148 
Basis set AUG-CC-PVQZ/MP2FIT generated. Number of basis functions:   194
...

AO(A)-basis ORBITAL           loaded. Number of functions:      84
RI(R)-basis CC-PVQZ/JKFIT     loaded. Number of functions:     148
DF-basis AUG-CC-PVQZ/MP2FIT   loaded. Number of functions:     194

When I specified the same basis set a little bit different
geomtyp=zmat
geometry={ Cl }
basis={
Cl=aug-cc-pvqz
}
rhf
rmp2-F12

MOLPRO used different density fitting basis sets.

Density fitting integral evaluation by F. R. Manby, 2003,2007

Basis set JKFIT generated for CL=AUG-CC-PVQZ. Number of basis functions:   184
Basis set JKFIT2 generated for CL=AUG-CC-PVQZ. Number of basis functions:   184
Basis set MP2FIT generated for CL=AUG-CC-PVQZ. Number of basis functions:   194
...

AO(A)-basis ORBITAL           loaded. Number of functions:      84
RI(R)-basis JKFIT2            loaded. Number of functions:     184
DF-basis MP2FIT               loaded. Number of functions:     194


Is it suppose to be like this? Does it mean that when I use F12 methods with standard basis sets like aug-cc-pvqz (and I don't need to explicitly define fitting basis) it would be better to specify basis set the second way?

Thank you very much.


Boris