  We investigate the role of correlations in the tetragonal and collapsed
tetragonal phases of CaFe2As2 by performing charge self-consistent DFT+DMFT
(density functional theory combined with dynamical mean-field theory)
calculations. While the topology of the Fermi surface is basically unaffected
by the inclusion of correlation effects, we find important orbital-dependent
mass renormalizations which show good agreement with recent angle-resolved
photoemission (ARPES) experiments. Moreover, we observe a markedly different
behavior of these quantities between the low-pressure tetragonal and the
high-pressure collapsed tetragonal phase. We attribute these effects to the
increased hybridization between the iron- and arsenic orbitals as one enters
the collapsed tetragonal phase.
