  We explore the effects of correlation on the ground-state energies and on
photoionization dynamics in atomic Be and Ne. We apply the time-dependent
restricted-active-space self-consistent-field method for several excitation
schemes and active orbital spaces with and without a dynamic core to address
the effects systematically at different levels of approximation. For the
ground-state many-electron wave functions, we compare the correlation energies
with entropic measures of entanglement. A larger magnitude of the correlation
energy does not always correspond to a larger value of the considered
entanglement measures. To evaluate the impact of correlation in a process
involving continua, we consider photoionization by attosecond pulses. The
photoelecton spectra may be significantly affected by including a dynamical
core.
