Different Slater exponents can be used for core-core, core-valence and valence-valence pairs
as described in H.-J. Werner, G. Knizia, and F. R. Manby (Mol. Phys., submitted).
The exponents are specified using the
GEM_BETA option, e.g., GEM_BETA=[1.0, 1.7, 2.5] (see options, section 31.6).
The three values are used for vv, cv, cc pairs, respectively. In most cases, core pairs can
be defined by using the CORE directive: all orbitals that are not core and do not belong
to the default valence shell are then treated as core. If part of the default valence shell
is to be taken as core (e.g., the 3d shell in first-row transition metals), the core can be
defined via the PRCORE variable, e.g., prcore=[4,2,2,1,4,2,2,1] for Cu
. This
variable must then be defined before the F12 calculation that should use it. The following
example shows calculation for Br, in which the 
shell is treated as core.
molpro@molpro.net 2012-02-11