By default, Molpro only correlates the valence electrons. Inner-shell correlation
can be activated using the CORE directive. On this directive the number
of core orbitals (not correlated) in each symmetry is given. Just CORE
without any numbers means that all electrons are correlated. For example
Normally, it is sufficient to correlate in the electrons in the shell.
Note that it makes no sense at all to activate core correlation without
using appropriate basis sets. Whenever available, we recommend to use
the cc-pwCVZ or aug-cc-pwCVZ basis sets.