  Recently, we have introduced a new generation of effective core potentials
(ECPs) designed for accurate correlated calculations but equally useful for a
broad variety of approaches. The guiding principle has been the isospectrality
of all-electron and ECP Hamiltonians for a subset of valence many-body states
using correlated, nearly-exact calculations. Here we present such ECPs for the
3d transition series Sc to Zn with Ne-core, i.e, with semi-core 3s and 3p
electrons in the valence space. Besides genuine many-body accuracy, the
operators are simple, being represented by a few gaussians per symmetry channel
with resulting potentials that are bounded everywhere. The transferability is
checked on selected molecular systems over a range of geometries. The ECPs show
a high overall accuracy with valence spectral discrepancies typically $\approx$
0.01-0.02 eV or better. They also reproduce binding curves of hydride and oxide
molecules typically within 0.02-0.03 eV deviations over the full
non-dissociation range of interatomic distances.
