  We have studied neutron-rich calcium isotopes in terms of the shell model
employing a realistic effective interaction derived from the CD-Bonn
nucleon-nucleon potential. The short-range repulsion of the potential is
renormalized by way of the V-low-k approach. The calculated results are in very
good agreement with the available experimental data, thus supporting our
predictions for the hitherto unknown spectra of 53-56Ca nuclei. In this
context, the possible existence of an N=34 shell closure is discussed.
