  Transfer reactions are essential to determine spectroscopic factors and
astrophysical reaction rates. However, their theoretical evaluation is
typically effected using standard reaction theory, from which structure degrees
of freedom are absent. While reaction cross sections have been implemented in
the frame of the no-core shell model with continuum, this model can be applied
in practice only to the lightest nuclei. The use of the core + valence nucleon
picture is then necessary to include inter-nucleon correlations in reaction
cross sections involving medium nuclei. For this, we will use the recently
developed coupled-channel Gamow Shell Model (GSM-CC) for direct reactions and
extend it to the evaluation of transfer cross sections. As an example, we will
study the ${ { }^{ 40 } }$Ca(d,p) transfer reaction with GSM-CC. Experimental
data can be successfully reproduced, but at the price of the use of a very
phenomenological Hamiltonian.
