  Fragmentation of the dipole strength in the N=82 isotones 140Ce, 142Nd and
144Sm is calculated using the second random-phase approximation (SRPA). In
comparison with the result of the random-phase approximation (RPA), the SRPA
provides the additional damping of the giant dipole resonance and the
redistribution of the low-energy dipole strength. Properties of the low-energy
dipole states are significantly changed by the coupling to
two-particle-two-hole (2p2h) states, which are also sensitive to the
correlation among the 2p2h states. Comparison with available experimental data
shows a reasonable agreement for the low-energy E1 strength distribution.
